HSA Calculator
Contribution, return & tax
Your result will appear here
Fill in the fields on the left and this updates as you type.
Know what this estimate is based on
- Jurisdiction
- United States — state-regulated insurance
- Scope and limitations
- Educational estimate only. Insurance in the U.S. is regulated state by state, so rates, required coverages and available discounts differ by where you live. Your premium is set by an insurer's own underwriting — driving record, claims history, credit-based insurance score where permitted, the property itself — and only a quote is binding. What a policy pays depends on its exclusions and limits, not on this estimate.
- 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 amount you plan to contribute to your HSA each year.
- 02
Set the number of years you'll keep contributing and the expected annual return on the invested balance.
- 03
Add your marginal tax rate so the tool can show the income tax each contribution saves.
- 04
Open Advanced options to enter a starting HSA balance you already hold and see how it lifts the final projection.
Formula
The calculator grows your health savings account one year at a time. Each year the running balance is multiplied by (1 + return rate) and then your annual contribution is credited at the end of that period, so the formula applied every year is balance = balance × (1 + r) + annualContribution, where r is the expected return written as a decimal. After the chosen number of years the final balance is the headline 'Projected HSA balance'. Total contributions are simply startingBalance + annualContribution × years, and investment growth is the projected balance minus those contributions — the part the market added rather than you. Because contributions are credited at period end and a fresh account starts empty, leaving the advanced 'Starting HSA balance' at its default of 0 reproduces the ordinary-annuity future value exactly: balance = annualContribution × ((1 + r)^years − 1) ÷ r. Set a starting balance above zero and that opening lump sum is added at the front and compounds for the full term on top of the annuity, raising both the balance and the growth figure. Alongside the projection the tool reports the tax side: annual tax saving = annualContribution × taxRate ÷ 100, the income tax your pre-tax contribution avoids each year, and the lifetime saving shown in the insights is that annual figure multiplied by the number of years.
Example
Take the default inputs: you contribute 100,000 a year for 20 years, expect a 6% return, sit in the 24% marginal tax bracket, and start from a 0 balance. Year one the empty account grows to 0 × 1.06 + 100,000 = 100,000. Year two it becomes 100,000 × 1.06 + 100,000 = 206,000, year three 206,000 × 1.06 + 100,000 = 318,360, and so on, each year compounding the prior balance at 6% before the new 100,000 is added at period end. Carry that forward through all 20 years and the projected HSA balance reaches 3,678,559. You only paid in 100,000 × 20 = 2,000,000, so investment growth accounts for 3,678,559 − 2,000,000 = 1,678,559 of the total — the market did more of the work than your deposits did. Because a 0 start reproduces the annuity formula, you can check it directly: 100,000 × ((1.06^20 − 1) ÷ 0.06) = 100,000 × 36.78559 = 3,678,559. On the tax side, each 100,000 contribution avoids 100,000 × 24 ÷ 100 = 24,000 of income tax, so the annual tax saving is 24,000 and over 20 years contributions cut your tax bill by about 24,000 × 20 = 480,000.
Definitions
- Annual contribution
- The amount you pay into the HSA each year, credited at the end of every period and the source of all future deposits (0 to 2,000,000).
- Years
- How many years you keep contributing and let the account compound — often from now until you stop working or expect large medical costs (1 to 50 years).
- Expected return
- The average annual investment return on the invested HSA balance; cash left uninvested earns close to 0%, while a diversified portfolio targets a higher figure (0% to 15%).
- Marginal tax rate
- The income tax rate on your top dollars, used to value the upfront deduction — each contribution avoids tax at this rate (0% to 60%).
- Starting HSA balance
- An advanced input for money already in the account; it is added at the front and compounds for the whole term, and at its default of 0 the projection follows the plain annuity formula (0 to 5,000,000, default 0).
- Projected HSA balance
- The headline result: the account value after all years of contributions and tax-free compounding, equal to total contributions plus investment growth.
Good to know
The one account with three tax breaks
A health savings account is unusual because it is taxed favourably at every stage money passes through it, and understanding those three breaks is the key to using it well. First, contributions are made pre-tax, so every amount you put in is subtracted from the income you are taxed on that year — at a 24% marginal rate, a 100000 contribution hands back 24000 you would otherwise have sent to the tax authority. Second, the balance grows tax-free: interest, dividends and capital gains inside the account are never taxed while they accumulate, unlike an ordinary brokerage account where each gain chips away at the compounding. Third, withdrawals spent on qualified medical expenses come out completely tax-free, at any age and with no penalty. No other widely available account stacks all three advantages in one place; a traditional retirement account skips the tax-free withdrawal, and a regular savings account skips the deduction and the tax-free growth. The calculator deliberately reports two distinct numbers because of this structure. The projected balance captures the tax-free growth and the eventual tax-free spending power, while the annual tax saving captures the upfront deduction. Treating them separately stops you from undervaluing the account: someone who looks only at the final balance forgets the years of tax already avoided on the way in, and someone who looks only at the deduction misses the decades of untaxed compounding. To be eligible, you must pair the HSA with a qualifying high-deductible health plan, which is why this tool sits alongside the health-insurance and high-deductible comparisons — the account only opens once you have the right plan behind it.
Reading the chart and finding the crossover year
Below the headline numbers the tool draws a growth chart and a year-by-year table, and learning to read them turns an abstract projection into a story you can act on. The chart plots two lines that begin together and then fan apart: a balance line tracing the account's value and a contributions line tracing the cumulative cash you have actually deposited. At the start the two lines are almost on top of each other, because hardly any tax-free growth has had time to build, so the slim wedge between them is the only interest you have earned so far. As the years roll on the wedge widens, and the rate at which the balance line pulls away from the flat-sloping contributions line is the visual signature of compounding gathering speed. The table beside it puts numbers to that picture, listing each year alongside its contributions, balance and a growth column that is simply the balance minus what you have paid in — the same wedge, read as a figure rather than a gap. The single most informative milestone to hunt for is the crossover year: the first year in which the growth column's annual increase outpaces a single year's contribution, the point where the account earns more for you than you feed it. Locating it tells you a lot about your inputs. An early crossover signals a generous return or a long runway already doing real work, while a crossover that never arrives within your chosen horizon is a hint that the term is too short or the return too cautious for compounding to take charge. Watching that milestone move as you adjust the inputs is often more persuasive than any single ending balance.
Why time and contributions both matter
The projected balance is driven by three levers — how much you contribute, for how many years, and what return you earn — but they do not pull with equal force. Years is the quiet powerhouse because compounding is exponential: a contribution made in the first year is multiplied by the return many more times than one made near the end, so a long horizon turns modest deposits into a large balance. With the default inputs, contributions of 2000000 grow to 3678559, meaning the 1678559 of growth came almost entirely from giving early deposits time to compound tax-free. Shorten the term and that growth shrinks far faster than the contributions do, because you are cutting off the most valuable compounding years at the back end. The annual contribution sets the base the returns work on; doubling it roughly doubles the final balance, but it cannot manufacture the time that compounding needs. The expected return is the multiplier that links the two — a higher return widens the gap between contributions and balance dramatically over a long horizon, while a near-zero return collapses the projection back to little more than the sum of your deposits. The practical lesson is to start contributing as early as eligibility allows and to keep the money invested for as long as you can, rather than spending the balance down each year on routine medical bills. An HSA used as a long-horizon, invested account behaves very differently from one drained annually; the calculator lets you see both by changing the years and the return, and the contrast is usually stark enough to change behaviour.
Putting a value on the tax deduction
The growth side of an HSA gets the attention, but the upfront tax saving is a real, immediate return that the calculator quantifies through the marginal tax rate field. Your marginal rate is the percentage you pay on your top slice of income, and because HSA contributions reduce that taxable income, each contribution avoids tax at exactly that rate. The tool computes the annual tax saving as contribution × tax rate ÷ 100 — 24000 a year on the default 100000 contribution at a 24% rate — and the insights extend this to roughly 480000 over the 20-year term. It is worth being clear about what this number is and is not. It is not part of the projected balance; it is money you keep in your pocket each year by contributing pre-tax, effectively a discount on the cost of funding the account. If you are in a higher bracket the deduction is worth more, which is part of why HSAs are especially attractive to higher earners who also have the cash flow to leave the balance invested. The marginal rate you enter should reflect the bracket your contribution actually falls in, not your average tax rate across all income, since the deduction comes off the top. Some savers prefer to take that annual saving and invest it elsewhere, which compounds the benefit further; others simply enjoy a lower tax bill. Either way, viewing the deduction as a separate stream alongside the balance gives a fuller picture of why the account is worth funding ahead of an ordinary taxable investment that offers no such break.
Using the starting balance and advanced options
Most of the inputs describe a forward-looking plan, but the advanced starting HSA balance field anchors the projection to where you actually are today. By default it is 0, which models a brand-new account and makes the result match the clean annuity formula for someone beginning from scratch. Enter a figure, though, and that opening sum is placed at the very front of the timeline and compounds for the entire term on top of every contribution you add. The effect is larger than people expect, because that money gets the maximum number of compounding years — more even than your first annual contribution, which only lands at the end of year one. A starting balance of a few hundred thousand can add well over that amount to the final figure across a long horizon, since it rides the full curve of tax-free growth. This is why anyone with an existing HSA should populate the field rather than leaving it at zero: omitting it understates both the projected balance and the investment-growth stat, sometimes substantially. The field is capped at 5,000,000 to keep projections realistic. Because it is tucked under advanced options, the calculator stays uncluttered for a first-time saver while still letting an established account-holder produce an accurate forecast. A good habit is to update this number each year with your real balance and re-run the projection; doing so keeps the forecast honest as markets move and as you contribute, and it lets you check whether your account is tracking ahead of or behind the path you originally planned.
Common mistakes that shrink an HSA
An HSA can be one of the most powerful accounts available, but several avoidable habits quietly cap its growth, and the calculator makes each of them visible. The most common is leaving the entire balance in cash. Many providers default new contributions into a low-yield holding account, so unless you actively choose investments the money earns almost nothing — set the expected return near 0% and the projection collapses to little more than your deposits, with the growth figure nearly vanishing. The second mistake is spending the account down every year on routine medical bills. Doing so is permitted and tax-free, but it resets the compounding clock and forfeits the long-horizon growth that gives the HSA its edge; where cash flow allows, paying small medical costs from a regular account and keeping the HSA invested produces a far larger balance, as raising the years input demonstrates. A third pitfall is under-contributing relative to the annual limits, leaving valuable tax-advantaged space unused that cannot be reclaimed in later years. A fourth is forgetting to keep receipts: qualified medical expenses can be reimbursed from the HSA years later, so disciplined record-keeping lets you withdraw tax-free in the future against bills you paid out of pocket today, effectively letting more of the balance compound in the meantime. Finally, some savers stop contributing the moment they switch off a high-deductible plan and never invest what remains, letting an account that could have kept growing stagnate. Run the projection with realistic, sustained contributions and a genuine investment return, and the difference between an actively managed HSA and a neglected cash one is usually large enough to justify fixing these habits today.
Frequently asked questions
What does triple tax-advantaged mean for an HSA?
An HSA is taxed favourably at all three stages: contributions go in pre-tax and cut your taxable income, the balance grows tax-free with no tax on interest, dividends or gains, and withdrawals for qualified medical expenses come out tax-free too. No other common account combines all three breaks. That is why the calculator tracks both the projected balance and the yearly tax saving — together they capture the account's full value.
Why is the investment growth so much larger than what I contributed?
With the default inputs you pay in 2000000 over 20 years but the balance reaches 3678559, so growth of 1678559 exceeds your deposits. Early contributions compound for nearly two decades, and because the gains are never taxed along the way, the whole balance keeps working. Leaving the money invested rather than holding it as cash is precisely what produces that growth — a 0% return would leave you with only your 2000000.
Should I invest my HSA or keep it in cash?
Many HSAs sit in a cash account earning almost nothing, which the calculator would show by setting the expected return near 0%. If you can cover near-term medical bills from elsewhere, investing the balance lets the triple tax advantage compound for years or decades. The expected-return field lets you compare a cash-like rate against a long-term portfolio rate to see the difference in the final balance.
How is the annual tax saving calculated?
It is your annual contribution multiplied by your marginal tax rate: with a 100000 contribution and a 24% rate that is 24000 saved every year. The saving comes from the upfront deduction — contributing pre-tax lowers the income you are taxed on. Over the 20-year default term those yearly savings add up to roughly 480000, separate from and on top of the investment growth in the balance.
Can I use this for retirement, not just medical costs?
Yes. After age 65 you can withdraw HSA funds for any purpose without penalty, paying only ordinary income tax — much like a traditional retirement account — while medical withdrawals stay tax-free at any age. That makes a well-funded, invested HSA a powerful supplementary retirement vehicle. Set a long number of years to model holding the account well into retirement rather than spending it each year.
What should I put in the starting HSA balance field?
Enter any money already sitting in your HSA today; it is an advanced input that defaults to 0 for a brand-new account. Because that opening sum compounds for the full term on top of your contributions, even a modest existing balance noticeably lifts the projection. Leaving it at 0 makes the result match the standard annuity future-value formula for a fresh account.