Student Loan Calculator

Background.

A student loan calculator answers the question every borrower actually has the moment a federal or private loan is disbursed: what will this cost every month, and in total, from the day the money lands to the day the balance hits zero? This calculator is built specifically around the mechanics of student debt rather than a generic installment loan, because student loans behave differently from a car loan or personal loan in one important way — most borrowers do not start repayment the day the loan is disbursed. Federal Direct Loans carry a standard six-month grace period after you graduate, leave school, or drop below half-time enrollment, and for Direct Unsubsidized Loans and Direct PLUS Loans, interest keeps accruing every day of that grace period even though no payment is due. The day repayment begins, that accrued interest capitalizes — it gets added to your principal balance — so your monthly payment for the next ten years (or however long your term runs) is calculated against a balance that is larger than what you originally borrowed. Direct Subsidized Loans are the one exception: the federal government pays the interest during the grace period, so the balance at repayment start equals the balance at disbursement exactly.

Enter your disbursed balance, your interest rate, your repayment term, the length of your grace period, and whether interest accrues during that period, and this calculator runs both halves of the problem: the grace-period accrual and capitalization, and the standard amortizing-loan formula on the post-capitalization balance. The output is your monthly payment, the dollar amount of interest that capitalized before you made a single payment, the principal your payment is actually calculated against, the total amount you will pay over the life of the loan, the all-in interest cost from disbursement to payoff, and the total number of months — grace period included — from disbursement to a zero balance.

Rates matter enormously here because federal student loan rates are not static across years the way a 30-year fixed mortgage rate is quoted once and done. Congress fixed the rate-setting mechanism in the Bipartisan Student Loan Certainty Act of 2013: each July 1, the Department of Education sets a new fixed rate for that year's disbursements, equal to the high yield of the final 10-year Treasury note auction before June 1, plus a statutory add-on that varies by loan type — 2.05 percentage points for undergraduate Direct Subsidized and Unsubsidized loans, 3.60 points for graduate Direct Unsubsidized loans, and 4.60 points for Direct PLUS loans, each subject to a statutory cap. For loans first disbursed between July 1, 2026 and June 30, 2027, those rates are 6.52% for undergraduate loans, 8.07% for graduate Unsubsidized loans, and 9.07% for PLUS loans — set from a 10-year Treasury auction high yield of 4.468% on May 12, 2026. Once your rate is fixed at disbursement, it never changes for the life of that loan, even though next year's borrowers get a different rate.

This calculator models the standard federal Repayment Plan structure: a fixed rate, a fixed term (10 years is standard; Extended plans run up to 25), and equal monthly payments once repayment starts. It does not model income-driven repayment, where your payment is a percentage of discretionary income rather than a function of balance, rate, and term — use Quanta's discretionary income calculator for that half of the picture, and the Public Service Loan Forgiveness payment counter if you are pursuing PSLF. It also does not model private-loan variable rates that reset periodically; if your private loan is variable, re-run this calculator whenever your rate changes to get an updated payment estimate. Below the widget you will find the full formula, a worked example showing exactly how a $30,000 unsubsidized loan behaves from disbursement through a 10-year payoff, eight FAQs covering the federal-versus-private distinction, capitalization, and repayment-plan alternatives, and citations to the Federal Register, Federal Student Aid, and studentaid.gov.

What is student loan calculator?

A student loan is credit extended specifically to finance postsecondary education, and in the United States it comes in two broad families with very different terms. Federal student loans are issued directly by the U.S. Department of Education under the William D. Ford Federal Direct Loan Program and include Direct Subsidized Loans (undergraduate, need-based, no interest accrual while in school or during the grace period), Direct Unsubsidized Loans (available to undergraduate and graduate students regardless of need, interest accrues from disbursement), and Direct PLUS Loans (available to graduate students and parents of dependent undergraduates, higher rate, credit check required). Federal loan rates are fixed by statute each July 1 and are identical for every borrower of that loan type that year — your credit score does not affect your federal student loan rate. Private student loans are issued by banks, credit unions, and other lenders, are underwritten on creditworthiness (often requiring a cosigner for undergraduates), can carry fixed or variable rates, and do not carry the borrower protections attached to federal loans — income-driven repayment, Public Service Loan Forgiveness eligibility, deferment and forbearance rights, and discharge in the event of death or total permanent disability. The defining mechanical feature this calculator models is capitalization: when a loan enters a period where payments are not required (in-school status, the grace period, deferment, or forbearance) but interest continues to accrue, that unpaid interest is added to the principal balance at the end of the period, and every future interest charge and payment amount is calculated against the new, larger balance. Direct Subsidized Loans are shielded from capitalization during the in-school and grace periods because the federal government pays that interest directly; every other federal loan type, and most private loans, capitalize.

How to use this calculator.

1. 01Enter the loan balance at disbursement — the actual amount that was paid out to you or your school, not including interest that has not yet accrued.
2. 02Enter your annual interest rate. For federal loans disbursed between July 1, 2026 and June 30, 2027, use 6.52% for undergraduate Direct Subsidized/Unsubsidized, 8.07% for graduate Direct Unsubsidized, or 9.07% for Direct PLUS. Otherwise use the rate on your loan documents.
3. 03Enter your repayment term in years. 10 years is the federal Standard Repayment Plan; Extended plans run up to 25 years for qualifying balances.
4. 04Enter the grace period in months between disbursement and the first required payment. 6 months is the federal standard; set to 0 if repayment starts immediately.
5. 05Select whether interest accrues during the grace period. Choose "No" only for Direct Subsidized Loans; choose "Yes" for Direct Unsubsidized, Direct PLUS, and most private loans.
6. 06Read the outputs: your monthly payment, how much interest capitalized before repayment began, the principal your payment is actually based on, total paid over the term, the all-in interest cost, and the total months from disbursement to payoff.
7. 07Compare scenarios: re-run with interestAccrualDuringGrade set to "no" to see exactly how much a subsidized loan saves you versus an otherwise-identical unsubsidized loan, or shorten the term to see the total-interest tradeoff.

The formula.

Reviewed on 2026-07-27 against the Federal Register's 2026-27 rate notice and Federal Student Aid guidance. The calculator first determines capitalized interest: if interest accrues during the grace period, C = loanBalance × (annualRate ÷ 100) × (gracePeriodMonths ÷ 12), a simple-interest approximation of the daily interest accrual federal servicers actually use. If the loan is subsidized, C = 0. The principal at repayment start is P + C. From there the calculator applies the standard amortizing-loan formula: the periodic rate r is the annual rate divided by 100 and by 12, n is the term in years multiplied by 12, and the monthly payment is (P+C) × [r(1+r)ⁿ] / [(1+r)ⁿ − 1]. When r = 0 the formula collapses to (P+C) ÷ n, avoiding a division-by-zero on a rare zero-interest promotional loan. Total paid is the monthly payment multiplied by n, and the all-in total interest cost is total paid minus the original disbursed balance — meaning it captures both the capitalized grace-period interest and every dollar of interest charged during repayment. Months to payoff adds the grace period to the repayment term, giving the full disbursement-to-zero-balance timeline. All arithmetic uses arbitrary-precision decimal math to avoid floating-point drift over long terms.

A worked example.

Frequently asked questions.

References& sources.

1. [1]Federal Register (2026). Annual Notice of Interest Rates for Fixed-Rate Federal Student Loans Made Under the William D. Ford Federal Direct Loan Program. Document 2026-04065, published 2026-03-02.
2. [2]Federal Student Aid, U.S. Department of Education (2026). Interest Rates for Federal Direct Loans First Disbursed Between July 1, 2026 and June 30, 2027. Knowledge Center Electronic Announcement, 2026-06-04.
3. [3]Federal Student Aid — Interest Rates and Fees for federal student loans (grace period and capitalization mechanics).
4. [4]Federal Student Aid — Direct PLUS Loans overview and repayment terms.
5. [5]Internal Revenue Service — Topic No. 456, Student Loan Interest Deduction.
6. [6]Bipartisan Student Loan Certainty Act of 2013, Public Law 113-28 — statutory formula setting federal student loan interest rates from the 10-year Treasury note yield.