Student Loan Calculator
Estimate your student loan payment and payoff date, including interest that builds up in school or deferment, capitalization, and how much extra payments save.
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About this toolWhat is the Student Loan Calculator?
The Student Loan Calculator estimates the monthly payment and payoff date for a federal or private student loan on a fixed repayment plan. Enter the balance, interest rate and repayment term, plus how many months remain in school, grace or deferment before payments start.
Interest during that waiting period is where student loans differ from other debt. The calculator works out how much accrues, whether it is covered by a subsidy, whether you pay it as you go, and whether it is capitalized (added to the principal) when repayment begins. It then shows the payment, total interest, total paid, a balance chart and a repayment schedule.
Add an extra monthly amount to see how much sooner you finish and how much interest you avoid. Income-driven repayment plans are not modelled; see the note on the page for why.
- Interest during school, grace and deferment
- Subsidized, pay-as-you-go and capitalization options
- Payment, payoff date, total interest and total paid
- Extra monthly payments with months and interest saved
- Balance chart and repayment schedule with CSV export
How to use the Student Loan Calculator
- Choose the loan type to set sensible defaults for subsidy and capitalization.
- Enter the amount borrowed, the interest rate and the repayment term in years.
- Enter how many months remain before your first payment, counting school, the grace period and any deferment.
- Adjust the toggles if your loan is subsidized, if you will pay interest while in school, or if unpaid interest capitalizes.
- Read the payment, payoff date and total interest, add an extra monthly amount to compare, and open the schedule for detail.
Worked examples
Federal unsubsidized loan with a six-month grace period
Input
35,000 at 6.5%; 10-year term; 6 months until repayment; no capitalization
Output
1,137.50 of interest accrues; payment 410.12; total interest 14,214.46
Interest during grace is simple: 35,000 × 6.5% × 6/12. It stays separate from principal and is paid off first from the early payments, so it never earns interest.
Four years in school, interest capitalized
Input
35,000 at 6.5%; 48 months deferred; capitalized; 10 years
Output
9,100 accrued and capitalized; payment 500.75; total interest 25,089.59
Unpaid interest from four years of school adds 9,100 to the balance before the first payment. Paying that interest while in school, about 190 a month, would keep the payment at the 10-year level for 35,000.
Paying 100 extra a month
Input
First example plus 100 extra each month
Output
Paid off in 90 months instead of 120; 3,526.97 interest saved
Thirty fewer payments and a saving of about a quarter of the interest, from roughly 24% more each month.
Background and insight
Federal Direct loans charge simple interest: it accrues daily on the principal only, and unpaid interest does not itself earn interest unless it is capitalized. On a Direct Subsidized loan the government pays the interest while you are in school at least half-time, in the six-month grace period and during deferment. On Direct Unsubsidized and private loans, interest accrues from disbursement.
Capitalization adds unpaid interest to principal, after which you pay interest on it. Rules adopted by the US Department of Education in July 2023 removed most capitalization events for federal Direct loans, including entering repayment for the first time, though unsubsidized interest can still capitalize when certain deferments end. Private lenders generally capitalize when repayment starts. The loan type selector sets a sensible default and the toggle lets you match your promissory note.
The repayment payment is the standard amortization formula over the term (10 years on the federal standard plan). When interest is not capitalized, payments clear the outstanding interest first and the calculator solves for the level payment that repays everything within the term. Income-driven plans tie payments to income and family size and are being reshaped by 2025 legislation, so they are not estimated here; the Loan Simulator at StudentAid.gov uses your actual federal loan data.
Common use cases
Planning before graduation
See the payment you will face after the grace period and whether paying interest in school is worth it.
Choosing a repayment term
Compare a 10-year standard plan with 20 or 25-year extended terms and see the extra interest.
Deciding whether to prepay
Measure how much an extra payment each month shortens the loan.
Evaluating a refinance offer
Compare a private refinance rate and term with your current loan by running both.
Tips and limitations
- Federal loans have no prepayment penalty. Ask your servicer to apply extra payments to principal on the loan with the highest rate.
- Paying the interest while in school stops the balance from growing and is often cheaper than you expect.
- Several federal loans at different rates can be modelled one at a time, or as one balance at the weighted average rate.
- Refinancing federal loans into a private loan gives up federal protections such as income-driven repayment, deferment and forgiveness programs.
- Income-driven plans are not modelled. Use the Loan Simulator on StudentAid.gov for those.
Frequently asked questions
How is student loan interest calculated?
Federal loans use simple daily interest: balance × annual rate ÷ 365 for each day, charged on principal only. Monthly, that is about balance × rate ÷ 12. On 35,000 at 6.5%, interest is about 189.58 a month. Private loans usually work the same way but may compound or capitalize more often; check your loan agreement.
What does interest capitalization mean on student loans?
Unpaid interest is added to your principal, and from then on you pay interest on it too. Four years of unsubsidized interest on 35,000 at 6.5% is 9,100; capitalizing it raises a 10-year payment from about 397 to 500.75 a month.
Do subsidized loans accrue interest while in school?
No. For Direct Subsidized loans the Department of Education pays the interest while you are enrolled at least half-time, during the six-month grace period and during deferment. Turn on the Subsidized toggle to model that. Unsubsidized and private loans accrue interest throughout.
How long does it take to pay off student loans?
On the federal standard plan, 10 years. Extended plans run up to 25 years and income-driven plans longer. Extra payments shorten the time: 100 extra a month on a 35,000 loan at 6.5% cuts a 10-year plan to seven and a half years.
Is it worth paying student loan interest while in school?
If the interest would otherwise capitalize, yes: every dollar you pay then avoids interest on interest later. Even without capitalization it keeps your repayment balance down. On an unsubsidized loan it typically costs a modest monthly amount compared with the payment increase it prevents.
Does this calculator cover income-driven repayment plans?
No. Income-driven plans set payments from income and family size and some forgive the remaining balance, and they are being changed by legislation passed in 2025. The StudentAid.gov Loan Simulator uses your real federal loan data for those plans. This tool covers fixed payments: standard, extended and private loans.
Is there an in-depth guide to the Student Loan Calculator?
Yes. “Car Loans, Leases and Paying Off Debt: The Numbers That Matter” covers the background, how it works, common pitfalls and worked examples. Read the full guide.
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