Cash Deposit Growth Calculator
Savings & BankingWatch your cash deposits stack up and grow.
Your deposit plan
Advanced options
- Initial deposit$10,000
- Recurring deposits$30,000
- Interest earned$11,721
These projections assume the rate, deposits, tax and inflation stay constant for the whole period, with interest credited on the deposit rhythm you chose. Banks credit and compound in their own ways, so treat the figures as a close planning estimate rather than a quote.
Same money, different rhythm
The same $3,000 a year, split across each deposit rhythm — rate, time and tax unchanged.
| Rhythm | Each deposit | Deposits / yr | Final balance | vs your plan |
|---|---|---|---|---|
| Weekly | $58 | 52 | $51,768 | +$47 |
| Every 2 weeks | $115 | 26 | $51,754 | +$33 |
| MonthlyYour plan | $250 | 12 | $51,721 | — |
| Quarterly | $750 | 4 | $51,598 | −$122 |
| Yearly | $3,000 | 1 | $51,051 | −$670 |
Smaller, more frequent deposits get money earning sooner; with start-of-period timing a single yearly deposit can front-run them.
Growth over time
What moves the needle
The same time period with one lever nudged at a time.
- Current plan$51,721
- Deposits +50%$70,127
- Rate +1 pt$55,291
- Rate −1 pt$48,429
Deposit-by-deposit schedule
| Year | Deposits | Interest | Balance |
|---|---|---|---|
| 1 | $3,000 | $463 | $13,463 |
| 2 | $3,000 | $604 | $17,067 |
| 3 | $3,000 | $751 | $20,818 |
| 4 | $3,000 | $904 | $24,722 |
| 5 | $3,000 | $1,063 | $28,785 |
| 6 | $3,000 | $1,228 | $33,013 |
| 7 | $3,000 | $1,401 | $37,414 |
| 8 | $3,000 | $1,580 | $41,994 |
| 9 | $3,000 | $1,766 | $46,760 |
| 10 | $3,000 | $1,961 | $51,721 |
How this projection works
- A 4.00% nominal rate compounded monthly works out to a 4.07% effective annual yield — 0.3333% credited each deposit period.
- The plan runs 120 periods on a monthly rhythm (≈ 10 years), with $250 landing at the end of each period.
- Deposits of $40,000 plus $11,721 of interest kept produce the final balance of $51,721.
Know what this estimate is based on
- Jurisdiction
- General mathematical model
- Scope and limitations
- Projection only. Actual APY, posting dates, compounding, taxes, withdrawal rules, deposit protection, and fees depend on the financial institution and country.
- Source links checked
- Jul 30, 2026
Built and regression-tested by Smart Tools Lab. It has not been individually reviewed by a licensed financial, tax, or legal professional.
How to use
- 01
Enter the cash you are starting with, then the amount you plan to add and the rhythm it arrives on — weekly, every two weeks, monthly, quarterly or once a year.
- 02
Quote the rate the way your bank does: pick a nominal rate plus how often it compounds (daily up to yearly), or switch the toggle to APY if you already have the effective figure.
- 03
Set how long the money keeps growing in years and extra months, and open the advanced panel when deposits arrive at the top of each period, interest is taxed, or you want everything restated in today's money.
- 04
Read the final balance next to your total deposits, the interest credited, any tax withheld and the inflation-adjusted value, with warning chips flagging anything that undercuts the plan.
- 05
Scan the rhythm-comparison table to see what the same yearly money earns on each schedule, then follow the year-by-year rows or the deposit-by-deposit ledger to trace every credit.
Formula
The projection walks forward one deposit period at a time, on whatever rhythm you chose. First the rate is converted onto that grid: a nominal rate divided by its compounding frequency gives the rate per compounding step, and chaining those steps across one deposit period yields the exact per-period rate — so daily, monthly or yearly compounding is honoured without simulating every single day. If you quote an APY instead, the per-period rate is simply the rhythm-sized slice of that yearly yield. Each period the balance earns that rate, the chosen tax percentage is withheld from the credit on the spot, and your deposit joins at whichever end of the period your timing choice says. Because tax leaves with every credit, the balance that compounds is always the after-tax one. At the end, deposits plus interest kept equals the final balance exactly, and dividing by the accumulated inflation factor restates that balance in today's money.
Example
Say you park $5,000 and add $100 every week for 8 years at a 4.5% nominal rate with daily compounding, while 15% of each interest credit is withheld for tax and inflation runs at 2.5%. Daily compounding lifts the 4.5% quote to a 4.60% effective yearly yield, which the tool slices into a per-week rate; the withholding trims the working yield to 3.90% after tax. Over 416 weekly deposits you put in $46,600.00 in total ($5,000 up front plus $41,600 of weekly additions). The account credits $10,398.73 of interest along the way, of which $1,559.81 is withheld as tax, so $8,838.92 actually stays and compounds. The final balance lands at $55,438.92 — a 1.19× multiple on the money you deposited. After 2.5% inflation over the 8 years, that balance buys what $45,501.31 buys today, a reminder that the real prize is smaller than the nominal one. Every figure holds only while the rate, tax and deposit habit stay exactly as entered.
Definitions
- Initial deposit
- The cash already sitting in the account on day one. It compounds for the entire span, which is why the projection counts it separately from the recurring stream — an early dollar simply has more periods to earn than a late one.
- Recurring deposit
- The fixed amount you add on every period of your chosen rhythm. In the worked example it is $100 a week, which stacks to $41,600 over 8 years before a cent of interest is counted.
- Deposit rhythm
- How often fresh cash arrives: weekly, every two weeks, monthly, quarterly or yearly. The rhythm sets the simulation grid itself — a weekly plan is projected week by week — and the comparison table shows what the same yearly money earns on each of the five schedules.
- Compounding frequency
- How often a nominal rate is credited and folded back into the balance, from daily to yearly. More frequent compounding nudges the effective yield above the quoted figure; the tool converts whatever you pick into an exact per-period rate on your deposit rhythm.
- Nominal rate
- The headline rate a bank quotes before compounding is taken into account. A 4.5% nominal rate compounded daily actually yields 4.60% over a year — the calculator does that conversion for you and shows the resulting APY beside the rate field.
- APY (effective annual yield)
- The percentage the balance genuinely grows in one year once compounding is folded in. Quote your rate as an APY and the compounding selector disappears, because the yearly yield is already settled.
- Per-period rate
- The slice of the yearly yield applied on each step of your deposit rhythm — the exact rate that, repeated across a year's worth of periods, reproduces the APY. The explainer prints it so you can check the arithmetic yourself.
- Tax on interest
- The percentage withheld from every interest credit at the moment it lands, the way many banks deduct withholding tax at source. Because the tax leaves immediately, later periods compound on the after-tax balance — at 100% the balance can only ever equal your deposits.
- After-tax yield
- The effective annual growth of the balance once the per-credit withholding is counted — 3.90% in the worked example against a 4.60% gross APY. It is the honest rate to compare against inflation.
- Real value (today's money)
- The final balance deflated by the inflation rate over the whole span, answering what the future number will actually buy. The worked example's $55,438.92 shrinks to $45,501.31 of present-day purchasing power at 2.5% inflation.
- Growth multiple
- The final balance divided by every dollar you deposited, initial amount included. A multiple of 1.19× means each dollar you put in became a dollar and nineteen cents by the end of the plan.
- Deposit timing
- Whether each deposit lands at the start of its period, earning interest in that same period, or at the end, starting to earn one period later. Start-of-period timing always finishes at least as high, and the gap widens with bigger deposits and higher rates.
Good to know
Why the same money on a different rhythm ends differently
Take two savers who commit the identical $3,000 a year to the same account earning the same rate. One moves $250 across every month. The other waits and deposits the full $3,000 once a year in December. Twelve months later both accounts hold the same contributions — but not the same balance, because the monthly saver's early deposits have been earning interest all year while the annual saver's money sat elsewhere. Compounded over a decade, that head start adds up. The cadence comparison table on this page makes the effect concrete. Using the calculator's defaults — a $10,000 opening deposit, $3,000 a year of new money, 4% nominal interest compounded monthly, ten years — the same annual amount produces $51,767.94 on a weekly rhythm, $51,753.79 every two weeks, $51,720.78 monthly, $51,598.34 quarterly, and $51,050.75 yearly. Weekly beats yearly by $717.19. Notice the shape of the spread: the jump from yearly to quarterly is far bigger than the jump from monthly to weekly. Most of the benefit comes from not letting money idle for months at a time; slicing an already-frequent rhythm even finer adds only cents per deposit. That shape carries a practical message. If you currently save in one annual lump — a bonus, a tax refund, a year-end sweep — moving to even a quarterly rhythm captures most of the available gain. Pushing from monthly to weekly is worth doing only if it costs you nothing in effort, which, with automatic transfers, it often does. The rhythm selector at the top of the calculator lets you test your own numbers on all five cadences, and the comparison table restates the same yearly money on each so the only variable that changes is time in the account.
Nominal rate or APY: decoding what the bank actually quoted
Banks advertise interest two different ways, and the difference matters more than the fine print suggests. A nominal rate — often labeled the stated rate or simply the interest rate — tells you the raw annual percentage before compounding is taken into account. It only becomes meaningful once you also know how often the bank credits interest: daily, monthly, quarterly, semi-annually, or yearly. An APY (annual percentage yield), by contrast, already bakes the compounding in. It is the percentage your balance would actually grow in one year with no deposits or withdrawals, whatever the crediting schedule underneath. The calculator accepts either. In nominal mode you enter the stated rate and pick the compounding frequency from the bank's disclosure; the tool converts that pair into the true annual yield and reports it. In APY mode you enter the yield directly and no frequency question arises, because the answer is already inside the number. At the default 4% nominal compounded monthly, the tool reports an APY of 4.07% — the monthly crediting nudges the effective yield above the sticker rate. In the worked example used elsewhere on this page, 4.5% nominal with daily compounding comes out to a 4.60% APY — a slightly wider gap, since both the rate and the crediting frequency are higher there. Which mode should you use? Match the bank. US deposit accounts are required to disclose APY, so if you are copying a figure from a savings-account page, APY mode is usually the faithful choice. If a product sheet gives you a stated rate plus a compounding schedule — common for certificates and some money-market accounts — use nominal mode and let the tool do the conversion. What you should not do is type a nominal rate into APY mode or vice versa: at these rate levels the error is small, but it is an error you never need to make.
Your deposit schedule doesn't have to match the bank's clock
A natural worry when setting up this calculator: what happens if you deposit weekly into an account that compounds monthly, or yearly into one that compounds daily? Do the mismatched clocks break the math? They don't, because the engine converts the account's quoted rate into an exact rate per deposit period before it projects anything. Here is the conversion in plain words. First the tool works out how much one dollar grows over a full year under the bank's actual compounding schedule — that is the account's true annual yield. Then it asks: what single rate, applied once per deposit period, would produce exactly that same annual growth? On a monthly rhythm that means finding the rate which, applied twelve times, matches the year; on a weekly rhythm, fifty-two times. Formally, the per-period rate is (1 + nominal/m)^(m/p) − 1, where m is the number of compounds per year and p is the number of deposits per year; in APY mode it is simply (1 + APY)^(1/p) − 1. The projection then walks forward in deposit-sized steps while reproducing the account's annual yield exactly, so nothing is lost or gained in translation. The practical consequence is freedom. You can choose the rhythm that suits your paycheck — weekly, biweekly, monthly, quarterly, or once a year — without worrying about whether it lines up with the account's compounding frequency, and you can compare accounts with different compounding schedules on the same deposit rhythm. When you switch rhythms in the cadence table, only the timing of your money changes; the underlying yield stays anchored to the rate quote you entered. Any difference you see between rows is therefore genuinely about when deposits arrive, never an artifact of the two clocks disagreeing.
When tax comes out of every interest credit
Savers meet tax on interest in one of two ways: the bank withholds a slice of each interest payment before it reaches the account, or the interest arrives whole and the tax gets settled later. This calculator models the first arrangement — withholding at source — and models it precisely. Each time interest is credited, the tax rate you enter is skimmed off that credit immediately, and only the remainder joins the balance. Mechanically, the effective per-period growth rate becomes the gross rate multiplied by (1 − tax rate). That timing detail changes the arithmetic of growth, not just the total. Because tax leaves the account the moment interest lands, the balance that compounds forward is always the after-tax one. Withheld dollars never spend a day earning; the drag compounds along with everything else. In the worked example on this page — $5,000 up front plus $100 weekly at 4.5% nominal with daily compounding, over eight years with 15% withheld from each credit — the account generates $10,398.73 of gross interest, gives up $1,559.81 in withholding, and keeps $8,838.92. The summary translates the same drag into yield terms: a 4.60% APY becomes a 3.90% after-tax yield. The alternative arrangement — collecting interest in full all year and paying the tax bill once at filing time — is deliberately not modeled here. Under a year-end settlement the pre-tax interest keeps compounding until the payment date, so the account ends slightly ahead of the at-source case even at the same tax rate, and the payment comes from somewhere outside the projection. If that is your situation, treat this tool's after-tax figures as a mildly conservative estimate. And since withholding rules and rates vary by country and account type, the tax field is a modeling input, not tax advice.
First day of the period or last: what the timing toggle changes
Every recurring deposit in this projection lands on a schedule, and the timing toggle decides which edge of the schedule it lands on. With end-of-period timing — the calculator's default — each deposit arrives just as its period closes, after that period's interest has been calculated. With start-of-period timing the deposit arrives on day one, so it participates in its own period's interest immediately. The initial deposit is unaffected; it is in the account from the first moment either way. The mechanical difference is simple: under start timing, every recurring deposit earns exactly one extra period of interest, which then compounds from that point on. How much that matters depends on how big a period is. On a weekly rhythm, one period of head start is a single week's interest per deposit — real, but small. On a yearly rhythm, one period is a full year, so shifting a yearly deposit from the end of the plan year to its beginning gives each contribution twelve extra months of growth. In other words, the coarser your rhythm, the more the toggle matters; timing and cadence are two views of the same underlying question, which is how long your money idles before it starts working. The gap also widens with the interest rate and the horizon. One extra period per deposit is worth more at a higher rate, and each of those head starts then compounds for however many years remain, so early deposits in a long plan benefit most. In practice, choose the setting that matches reality: if your transfer fires the day you are paid, start-of-period is the honest choice; if you sweep whatever is left at the end of the month, end-of-period fits. Flip the toggle and watch the final balance move — the difference is the price of waiting, stated in dollars.
The balance you'll see versus the groceries it will buy
A deposit projection always produces two honest answers to "how much will I have?" The first is the nominal balance — the number the bank's app will actually display at the end. The second is the real value: what that balance will be worth in today's purchasing power, after prices have had years to drift upward. This calculator reports both, using the inflation rate you enter to deflate the final balance into today's money. The worked example shows how far the two can drift apart even at moderate inflation. Saving $100 a week on top of a $5,000 start, at 4.5% nominal with daily compounding and 15% tax withheld, grows to a final balance of $55,438.92 after eight years. At 2.5% annual inflation, that balance buys what $45,501.31 buys today. Nothing was lost — every one of those dollars is real and spendable — but eight years of gently rising prices mean each dollar stretches less. Note what the deflation applies to: the whole ending balance, deposits included. Inflation does not only erode interest; it erodes the purchasing power of every dollar you parked along the way. This is the honest trade of cash saving. Deposits offer predictability and no risk of nominal loss — in this model the balance can only grow or stay flat — while the return is usually modest relative to inflation. The real value can even land below the nominal sum of deposits, as it does here: $45,501.31 of today's purchasing power against $46,600.00 put in, because most contributions had only part of the eight years to earn while inflation ran the full span. That does not make cash saving a mistake; emergency funds and near-term goals are exactly where nominal certainty matters most. It simply means the real-value line, not the headline balance, is the right number for judging long-horizon progress.
Small, frequent, automatic: the practical case for a tight rhythm
The cadence table earlier on this page makes the mathematical case for frequent deposits, and the honest verdict is that the math alone is modest: at the default settings, weekly beats yearly by $717.19 over ten years. The stronger case for a tight rhythm is behavioral, and it shows up in what actually gets deposited rather than in how fast deposits grow. A yearly or quarterly saving plan asks you to make a large decision a handful of times, usually when a lump of money is sitting in a checking account with competing claims on it. A weekly or biweekly plan asks you to make one small decision once — set up the transfer — and then never again. Small amounts survive contact with real life in a way large ones often don't: $100 leaving every Friday is rarely the difference between making rent and not, while a full year's contribution leaving every December competes with holidays, repairs, and everything else the year has saved up. The worked example on this page runs on exactly that pattern: 416 weekly deposits of $100 over eight years, $46,600.00 in total including the opening $5,000, moved without any single transfer ever feeling large. Two practical suggestions follow. First, match the rhythm to your income: if you are paid every two weeks, a biweekly transfer dated the day after payday removes the money before it starts to read as spendable. Second, automate it and then leave it alone — a standing transfer does not renegotiate with you each period the way a manual one does. The calculator's role in this is planning, not enforcement: use it to find a per-period amount your budget can sustain indefinitely, because in this projection, as in real accounts, the plan that keeps running is worth more than an ambitious one abandoned in month four.
Auditing your projection: the yearly table and the deposit ledger
Below the chart, the projection unpacks into two tables at different zoom levels. The yearly table summarizes each year of the plan: deposits made that year, the gross interest earned, the tax withheld, and the balance at year-end — plus a today's-money column when inflation is set. The per-deposit ledger zooms all the way in, one row per deposit period, showing the deposit that landed, the interest credited, the tax skimmed from that credit, and the running balance afterward. Together they let you audit every dollar of the headline number instead of taking it on faith. Both views obey a single identity: final balance equals total deposits plus interest kept — that is, the gross interest earned less the tax skimmed from each credit. At the calculator's defaults, that reads $51,720.78 as $40,000.00 deposited plus $11,720.78 of interest earned. The same identity holds row by row — each ledger balance is the previous balance plus that period's deposit plus that period's after-tax interest, nothing more — so any row can be checked by hand with simple arithmetic. A few patterns are worth looking for. Early rows are deposit-dominated: interest credits look small next to the money you are adding. Scan down the interest column and watch it climb as the balance builds; in a long enough plan there can come a year where interest kept rivals the year's deposits — the point where the account starts doing meaningful work on its own. If you entered a tax rate, set the interest column against the tax column to watch the withholding drag accumulate in dollars rather than percentages. And if you chose start-of-period timing, note that each row's deposit appears before that period's interest is computed, which is exactly the head start the timing section described. The tables are the proof; the summary cards are just the tables added up.
Four numbers, one story: multiple, APY, after-tax yield, interest kept
The summary strip condenses the whole projection into a handful of statistics, and they are most useful read together rather than one at a time. The growth multiple answers the bluntest question — how many dollars came out per dollar put in. It divides the final balance by total deposits: at the defaults, $51,720.78 out of $40,000.00 in is a 1.29× multiple, or 29 cents of growth for every dollar you deposited. The multiple depends heavily on time and on how front-loaded your deposits are: money deposited late in the plan has had little chance to grow, which is why long horizons carry higher multiples at the same rate, and why a big initial deposit lifts the multiple more than the same money drip-fed near the end. The two yield figures describe the engine rather than the outcome. APY is the account's true annual growth rate with compounding folded in — the rate your balance would experience before any tax. The after-tax yield is the same idea measured on the balance you actually keep, after withholding has skimmed each interest credit. In the worked example, a 4.60% APY becomes a 3.90% after-tax yield at 15% withholding; the spread between those two numbers is the tax drag expressed as a rate. Comparing your after-tax yield with your inflation assumption tells you at a glance whether the account is gaining or losing ground in real terms. Interest kept bridges the two views: it is the dollar amount the yields actually produced — gross interest minus tax withheld, $8,838.92 in that same example. If a result surprises you, start here. A lower multiple than expected usually traces to a short horizon or back-loaded deposits; a wide gap between APY and after-tax yield traces to the tax rate; and interest kept shows what that gap costs in actual dollars.
The fine print: what this projection assumes and what it ignores
Every number this calculator produces follows from a small set of deliberate simplifications, and knowing them is part of reading the results honestly. The interest rate is constant for the whole span: no promotional teaser expiring after three months, no rate cuts, no tiered balances. Real deposit rates move with the market, so a ten-year projection at today's rate is a scenario, not a forecast. Tax is one flat percentage withheld from every interest credit — the model does not know about allowances, graduated brackets, tax-free thresholds, or accounts where interest is sheltered entirely. If your effective rate on interest differs from the sticker rate, enter the rate you actually expect to bear. The account itself is idealized. Apart from the tax withheld from each interest credit, nothing else leaves: no withdrawals, no maintenance fees, no penalties, so the balance can only grow or stay flat. Sibling tools on this site handle goal planning with withdrawals and the drag of banking fees; this one deliberately isolates the pure deposit-and-compound story. Time is also tidied up: the engine counts in whole deposit periods, so a span that doesn't divide evenly into your rhythm — ten and a half years of yearly deposits, say — is rounded to whole periods, and the interface discloses the actual span used. A 100-year ceiling also sits deep in the engine as a guard, well past anything the inputs let an everyday plan reach. Within those walls the arithmetic is exact, and every figure reconciles down to the ledger. But the walls are real: rates change, life interrupts deposit schedules, and tax rules are more textured than one flat percentage. Treat the output as a disciplined estimate for comparing plans and rhythms — general information, not financial or tax advice — and revisit the projection whenever your rate, rhythm, or circumstances change.
Frequently asked questions
What does the Cash Deposit Growth Calculator do, and who is it for?
It projects how an initial deposit plus recurring cash deposits grow with interest over a span you choose. You pick a deposit rhythm — weekly, every two weeks, monthly, quarterly, or yearly — enter the rate either as a nominal rate with a compounding frequency or directly as an APY, and optionally add tax withheld from interest and an inflation rate. It is built for savers who move money into a savings or deposit account on a schedule and want to see where the routine leads, in both nominal and today's dollars. With the defaults — $10,000 up front plus $250 a month at 4% compounded monthly for 10 years — it projects a final balance of $51,720.78, of which $11,720.78 is interest. Alongside the headline it reports total deposits, tax withheld, interest kept, APY, after-tax yield, real value, and a growth multiple.
Does it matter how often I deposit if I'm saving the same amount per year?
Yes — and the deposit rhythm is this calculator's signature lever. The cadence-comparison table takes the same yearly money and replays it on all five rhythms over one shared whole-year window, keeping every other setting — deposit timing included — exactly as you set it. At the defaults ($10,000 up front plus the same $3,000 a year at 4% compounded monthly for 10 years, end-of-period deposits), weekly deposits end at $51,767.94, every two weeks at $51,753.79, monthly at $51,720.78, quarterly at $51,598.34, and yearly at $51,050.75 — so weekly beats yearly by $717.19. The pattern is intuitive: earlier slices of the same annual money spend more time earning interest. The dollar gap is real but modest, which is why the stronger case for a faster rhythm is usually habit — small, frequent deposits are easier to sustain than one big annual transfer.
Should I enter my bank's rate as a nominal rate or as an APY?
Enter it the way your bank quotes it. In the United States, the advertised headline on savings accounts is almost always APY (annual percentage yield), which already includes compounding — choose APY mode and you don't even need to know how often the account compounds. If your disclosure shows an "interest rate" next to a separate, slightly higher APY, that interest rate is the nominal rate; use nominal mode and set the compounding frequency the bank states. The two are close but not interchangeable — for example, 4.5% nominal with daily compounding works out to a 4.60% APY — so entering one in the other's mode will quietly skew the projection. When in doubt, the number labeled APY is the one to trust.
How much does the compounding frequency really matter?
Less than most savers expect at typical rates. At the defaults, 4% nominal compounded monthly comes out to a 4.07% APY — seven hundredths of a point above the quoted rate — and moving to daily compounding nudges that up only a little more. What matters more is that the calculator converts the account's compounding clock to your deposit rhythm exactly, using the per-period rate (1 + nominal/m)^(m/p) − 1, so a weekly depositor into a monthly-compounding account is modeled precisely rather than approximated. If you entered an APY directly, the compounding frequency doesn't apply at all, because APY already bakes it in. In short: pick the right rate, and don't lose sleep over the compounding schedule.
How is tax on my interest handled — and what happens if I set the tax rate to 100%?
Tax here is withheld at the source: every time interest is credited, the tax slice comes out immediately, and only the after-tax remainder stays in the account to keep compounding. That is deliberately different from settling a tax bill the following April, where the full gross interest would compound all year before you paid anything out of pocket — this tool models the withholding case, so it runs slightly conservative compared with a year-end bill. At a 100% tax rate, every credit is withheld in full, so the balance ends at exactly what you put in — the initial deposit plus every recurring deposit — and earns effectively nothing. How interest is actually taxed depends on your account type and jurisdiction, so treat the tax figures as an estimate, not tax advice.
What does the after-tax yield figure actually mean?
It is the annual growth rate your balance truly experiences once withholding is taken from every interest credit — the after-tax counterpart to the APY. In the worked example, the account's gross APY is 4.60%, but with 15% withheld from each credit the after-tax yield is 3.90%. It lands slightly below simply knocking 15% off the APY, because each withheld slice also forfeits the compounding it would have earned later. Use this number, not the gross APY, when comparing accounts or checking whether your cash is keeping ahead of inflation.
What does the "real value" number tell me?
It restates the final balance in today's purchasing power, deflating it by the inflation rate you enter across the full span. In the worked example — $5,000 plus $100 a week at 4.5% with daily compounding for 8 years, with 15% withholding — the account ends at $55,438.92, but after 2.5% yearly inflation that balance only buys what $45,501.31 buys today. The gap between the two numbers is the purchasing power surrendered while the cash sat parked. Inflation compounds against you just as steadily as interest compounds for you, so the adjustment matters most over long horizons. Leave inflation at zero and the final balance and real value are identical.
Should my deposits land at the start or the end of each period?
Pick whichever matches when your money actually moves. Start-of-period means each deposit arrives before that period's interest accrues, so it starts earning immediately — like an automatic transfer on payday at the top of the month. End-of-period means each deposit lands after the period's interest is credited, so it begins earning the following period. Whenever the account is earning anything after tax, start-of-period ends a little higher — roughly one extra period of interest on each deposit — and the gap widens with larger deposits and higher rates. If you're unsure, end-of-period is the conservative choice — and the calculator's default.
Why is the projected span slightly different from the years I entered?
The projection runs on a grid of whole deposit periods, so your span is rounded to a whole number of them and the page discloses the actual span it computed. On a monthly rhythm the grid is fine-grained, but on a yearly rhythm a span like 10.5 years has no natural home and gets rounded to whole yearly periods. Every output — balance, interest, tables — describes that disclosed span, not the raw entry. There is also a built-in 100-year ceiling deep in the engine, though the input ranges keep everyday plans far beneath it. The adjustment is not an error; the tool is just being explicit about the horizon it actually modeled.
Is the projected balance guaranteed?
No. The calculator holds the rate you entered constant for the entire span, but savings rates float — banks reprice with the market, and a rate that looks generous today can drop next quarter without notice. Deposit insurance may protect your principal at a bank, but nothing guarantees the future yield. Treat the outputs as a projection under stated assumptions: re-run it whenever your rate changes, and consider running a lower rate alongside your current one as a conservative case. These results are general information, not financial advice.
How do the yearly table and per-deposit ledger add up — and what should I look for in them?
Everything reconciles to a single identity: final balance = total deposits + interest kept, where interest kept is gross interest minus tax withheld. At the defaults, $40,000.00 of deposits plus $11,720.78 of interest equals the $51,720.78 final balance to the cent. The yearly table shows that split year by year, while the per-deposit ledger goes finer, listing each deposit in sequence with the running balance (very long plans show the first 520 rows) so you can trace exactly when each dollar arrived and what accrued between deposits — in the worked example, that ledger runs to 416 weekly deposits. A useful habit is to compare early rows against late ones: your deposit stays constant while the interest credited per period quietly snowballs. If the two views ever seem to disagree with the headline, check the disclosed actual span — they all describe the same whole-period grid.
How is this different from the Savings Calculator, and when should I use that one instead?
This tool is about the deposit habit itself: it treats your cash-deposit rhythm as the main lever, converts the bank's compounding clock to that rhythm exactly, withholds tax from each interest credit, and shows how the same yearly money performs on five different cadences. The Savings Calculator is goal-oriented — it's the one to reach for when you have a target amount and a deadline and want it solved backward (how much to save, what rate you'd need, how long it takes), or when withdrawals are part of the plan. If your question is "what does my deposit routine grow into?", stay here; if it's "what do I need to do to hit a number by a date?", use the Savings Calculator.
Can my balance ever go down in this projection?
The nominal balance can't fall here: the model includes no withdrawals and no bank fees, and tax only ever comes out of interest credits, never out of principal. The worst case — a 0% rate or 100% withholding — leaves the balance climbing by exactly your deposits and nothing more. Two caveats are worth knowing. First, purchasing power can still fall: in the worked example the $55,438.92 final balance is worth only $45,501.31 in today's money after 2.5% inflation — below the $46,600.00 nominally deposited over the years. Second, a real account can shrink for reasons this model deliberately leaves out, like monthly maintenance fees or your own withdrawals, so read "only up or flat" as a property of the projection, not a promise about your account.