Student Loan Interest While in School Calculator
What you borrow, and how long before the bills start
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
- General mathematical model
- Scope and limitations
- Educational estimate only. Confirm the assumptions, current rules, fees, and rounding that apply to your situation before making a decision.
- 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 unsubsidized loan you take each year and the number of years you will be enrolled at least half-time. The example uses $7,500 a year for four years, so $30,000 in all.
- 02
Leave the pay-as-you-go field at 0 to see what happens if you pay nothing while studying, which is what most students do. Set it to 1 to see the other world.
- 03
Enter what you could realistically put toward interest each month while studying. The example uses $50 — small enough to be possible on a student budget, and the page shows exactly what it buys.
- 04
Enter how long you expect to take repaying once the bills start. Ten years is the example. The rate, the six-month grace period and the grace capitalization switch are already filled in from the Federal Register and 34 CFR.
- 05
Read the headline, which is the interest that has quietly built up by the time you finish, then the balance that repayment actually starts at, and compare it against the amount you borrowed.
Formula
Interest accrues on each disbursement from the day it is paid out. Monthly interest = the outstanding principal x the annual rate ÷ 12. The page adds one year's borrowing at the start of each year of study, then accrues month by month, so the first year's money accrues for the whole degree and the last year's for one year. If you pay interest while studying, each payment is taken off the accrued interest first, and interest that has been paid can never capitalize. At the end of study the in-school deferment expires, which is the capitalizing event in 34 CFR 685.202(b): the unpaid accrued interest is added to the principal. Balance after capitalization = principal borrowed + unpaid accrued interest. Grace period interest = that balance x the annual rate ÷ 12 x the months of grace. The regulation does not list the end of grace as a capitalizing event, so by default this amount is owed but is not added to the principal. Monthly payment = B x i ÷ (1 − (1 + i)^−n), where B is the balance at repayment. What capitalization costs = the total repaid on the capitalized balance, minus what the same term would have cost on the principal alone.
Example
A student borrows $7,500 in unsubsidized loans each year for a four-year degree, $30,000 in all, at the 6.52% rate for loans first disbursed between 1 July 2026 and 30 June 2027. They pay nothing while studying and expect to take ten years to repay. Interest runs from the first disbursement. In year one the loan accrues $489, ending at $7,989. Year two adds $978 and ends at $16,467. Year three adds $1,467 and ends at $25,434. Year four adds $1,956 and ends at $34,890 — and by that final year the loan is accruing $190 a month, more than many students pay for a phone. By graduation $4,890 of interest has built up on $30,000 of borrowing. The in-school deferment then expires, and under 34 CFR 685.202(b) that $4,890 is capitalized into the principal, making $34,890. Six months of grace add a further $1,137, bringing the balance owed to $36,027 before a single payment is due. Repaying $34,890 over ten years costs $397 a month. The capitalization alone accounts for $6,669 of what they repay, and the loan costs $48,720 in total on $30,000 borrowed. Run again with $50 a month paid during study and grace. That costs $2,589 out of pocket across those years, but only $2,601 of interest capitalizes instead of $4,890, so repayment starts at $32,601. The payment falls to $371 a month, capitalization costs $3,547 instead of $6,669, and the loan costs $47,813 in total — $907 less, for payments small enough to fit around a part-time job.
Definitions
- Unsubsidized loan
- A federal Direct loan that charges interest from the day it is disbursed, including the years you are in school and the grace period. Available to undergraduate, graduate and professional students without a need test.
- Accrued interest
- Interest that has been charged but not yet paid or added to the principal. It sits alongside the loan until something causes it to capitalize or until you pay it.
- Capitalization
- Adding unpaid accrued interest to the principal balance, after which it earns interest of its own. Under 34 CFR 685.202(b) this happens on a loan with no interest subsidy when a deferment expires.
- In-school deferment
- The period during which a Direct Loan borrower carrying at least half the normal full-time load is not required to make payments (34 CFR 685.204(b)). Its expiry is what triggers capitalization on an unsubsidized loan.
- Grace period
- The six months after you stop attending at least half-time before the first payment is due (34 CFR 685.207(b)(2)(i)). Payments are not required, but interest on an unsubsidized loan keeps accruing.
Good to know
Interest starts the day the money arrives
The defining feature of an unsubsidized loan is that it begins charging interest from the moment it is disbursed, years before anybody asks you for a payment. Students almost universally underestimate this, and the reason is structural rather than careless: no bill arrives while you are enrolled, so there is nothing to prompt anyone to look. The worked example on this page borrows $7,500 a year for a four-year degree at the 6.52% undergraduate rate for 2026-27. Because the first year's money is outstanding for the whole degree, the second year's for three years and so on, the accrual compounds in a way that is easy to miss year by year and startling in total. Year one adds $489, ending at $7,989. Year two adds $978, ending at $16,467. Year three adds $1,467, ending at $25,434. Year four adds $1,956, ending at $34,890. By that final year the loan is quietly accruing $190 a month — more than many students spend on a phone and groceries combined — with no statement to show for it. Across the degree, $4,890 of interest has attached itself to $30,000 of borrowing before a single payment is due. It is worth being clear about which loans do this and which do not. A subsidized loan, available only to undergraduates with demonstrated financial need and capped at $3,500, $4,500 and $5,500 by year of study, has its in-school interest paid by the government, so a student with only subsidized loans graduates owing exactly what they borrowed. Everything else accrues: unsubsidized loans at every level, graduate and professional borrowing in its entirety since subsidized loans stopped being available to them in 2012, parent PLUS from the day of disbursement, and essentially all private student loans. Your servicer can tell you the current accrued interest on your account at any time, and it is worth looking at least once a year rather than discovering the figure at graduation.
Capitalization, and what the regulation actually says
Accrued interest sits alongside the loan without earning anything itself until an event causes it to be capitalized, which means added to the principal. After that it earns interest of its own, which is why the timing of capitalization matters so much more than its name suggests. This area has changed, and a great deal of material written before 2023 is now wrong, so it is worth stating precisely what the current regulation says. 34 CFR 685.202(b), read on 16 September 2026, contains two provisions. The first is a definition: the Secretary may add unpaid accrued interest to the borrower's unpaid principal balance, and this increase is called capitalization. The second is the only capitalizing event the regulation now lists: for a Direct Loan not eligible for interest subsidies during periods of deferment, the Secretary capitalizes the unpaid interest that has accrued upon the expiration of the deferment. That connects to the in-school period through 34 CFR 685.204(b), under which a Direct Loan borrower carrying at least half the normal full-time load is eligible for a deferment. So the in-school period is a deferment, an unsubsidized loan earns no interest subsidy during it, and the interest accrued while you studied is capitalized when that deferment expires — when you leave school. In the worked example the $4,890 joins the $30,000 at that point, making $34,890. What the regulation does not list is equally important. The 2023 changes removed several events that used to trigger capitalization, and the end of the six-month grace period is not among those now listed. This page therefore does not claim that grace-period interest capitalizes; it leaves that interest owed but outside the principal, and provides a switch to change the treatment if your servicer tells you it handles your account differently. Your servicer is the only authority on how a specific account is treated, and studentaid.gov is where the official position is published.
The grace period is a break from bills, not from interest
When you stop attending at least half-time, a six-month grace period begins before the first payment is due. The rule is in 34 CFR 685.207(b)(2)(i), and the period exists for a sensible reason: new graduates need time to find work and receive a first paycheck before a loan payment lands. What the grace period is not is a pause on interest. On an unsubsidized loan, interest continues to accrue throughout at the same rate as always, and it accrues on the newly enlarged balance, because capitalization has just happened. In the worked example the balance entering grace is $34,890 rather than the $30,000 borrowed, and six months at 6.52% on that figure adds $1,137. By the time the first bill arrives, $36,027 is owed on $30,000 of borrowing, and the student has not yet missed a payment or done anything wrong. Two practical points follow. The first is that the grace period is an excellent time to make voluntary payments if any income has started, precisely because there is no required payment competing for the money and anything paid goes straight against interest that would otherwise sit on the balance. The second is that the grace period can be used up. It is a one-time allowance for each loan: a student who leaves school, uses the six months, then returns and borrows again will generally not receive a fresh six months on the earlier loans. Reserve members called to active duty for more than thirty days are entitled to have that period excluded from the grace period, and to a full six months afterwards. It is also worth knowing that the grace period and repayment plan selection interact. Loans made on or after 1 July 2026 may be repaid under the standard plan or the Repayment Assistance Plan, and if no selection is made, the standard plan is assigned by default. The grace period is the window in which to make that choice deliberately rather than inherit it.
The cheapest move a student can make
Paying interest while you are still in school is the highest-return financial move available to most students, and it is striking how small the amounts involved are. Nothing requires it. No form has to be filed, there is no penalty for paying early, and a servicer will accept any payment at any time while you are enrolled. What it buys is the prevention of capitalization: interest you have already paid can never be added to your principal, so it never earns interest of its own for the whole repayment period that follows. The worked example puts $50 a month toward interest during the four years of study and the six months of grace. That costs $2,589 out of pocket, spread across four and a half years — the sort of sum a part-time job covers. In return, only $2,601 of interest capitalizes instead of $4,890, so repayment starts at $32,601 rather than $34,890. The monthly payment over ten years falls from $397 to $371, the cost attributable to capitalization falls from $6,669 to $3,547, and the loan costs $47,813 in total rather than $48,720. That is $907 saved for $2,589 paid, with the rest of the benefit arriving as a permanently smaller balance and a lower payment at the exact moment a new graduate is least able to afford one. The saving scales with the rate and the amount, so a graduate student borrowing $20,500 a year at 8.07% gains considerably more. If $50 a month is impossible, smaller amounts still work, and so does a single payment from a summer job or a tax refund. If nothing is possible, that is a normal position and the loan is not damaged by it — but it is worth knowing the number, which is why the page shows both worlds side by side. Log in to your servicer's site to see the accrued interest on your own account, and pay against it whenever there is anything spare.
Frequently asked questions
How much interest builds up while I am in school?
More than most students expect. On this page's example — $7,500 a year for four years at the 6.52% undergraduate rate — $4,890 of interest accrues on $30,000 of borrowing before you finish. The first year's money accrues for the whole degree, the second year's for one year less, and so on. Nobody sends a bill for it while you are enrolled, which is exactly why it goes unnoticed: by the final year the loan is quietly accruing $190 a month.
When does that interest get added to my principal?
When the in-school deferment expires. 34 CFR 685.202(b), read on 16 September 2026, says the Secretary may add unpaid accrued interest to the principal balance, and that for a loan not eligible for interest subsidies the Secretary capitalizes the unpaid interest 'upon the expiration of the deferment'. While you are enrolled at least half-time you are in an in-school deferment under 34 CFR 685.204(b). So in the example the $4,890 joins the $30,000, and the balance becomes $34,890.
Does interest capitalize at the end of the grace period too?
The current regulation does not say so, and this page will not claim what it cannot verify. The only capitalizing event 34 CFR 685.202(b) now lists is the expiration of a deferment on a loan that earns no interest subsidy; the 2023 changes removed several events that used to capitalize. The end of the grace period is not among those listed. The page therefore leaves grace interest uncapitalized by default and gives you a switch to change it if your servicer tells you otherwise. Your servicer is the one who can confirm how your own account is handled.
Is the grace period interest-free?
No. It is a break from payments, not from interest. In the example, six months of grace adds $1,137 on the newly capitalized balance of $34,890. On a subsidized loan the government pays your in-school interest; on an unsubsidized loan there is no such help at any point, so the grace period is simply six months in which the debt grows while you look for work.
What does capitalization actually cost me?
In the example, $6,669 extra across a ten-year repayment. That is the difference between repaying the $34,890 the loan has grown to and repaying the $30,000 actually borrowed. It is not a fee or a penalty — it is simply that from the moment interest joins the principal, you pay interest on your interest for every year that follows.
Should I pay the interest while I am still in school?
If you can spare anything at all, yes, and the amounts are small. Putting $50 a month toward interest while studying and through the grace period costs $2,589 out of pocket, but repayment then starts at $32,601 instead of $34,890, the monthly payment falls from $397 to $371, and the whole loan costs $907 less. There is no penalty for paying interest early, no form to file, and you can start or stop whenever you like — a servicer will accept any payment at any time while you are enrolled.
What is the difference between subsidized and unsubsidized here?
It is the whole of this page. On a subsidized loan the government pays the interest while you are enrolled at least half-time, so nothing accrues and nothing capitalizes — you graduate owing exactly what you borrowed. On an unsubsidized loan interest runs from the day the money is paid out. Subsidized loans go only to undergraduates with financial need, capped at $3,500, $4,500 and $5,500 by year of study, so most graduate borrowing and much undergraduate borrowing is unsubsidized.