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Student Loan Interest Calculator
See exactly how much interest your student loans will cost over the life of the loan — and how the term changes it.
Short answer
Total student loan interest is what you pay on top of the amount you borrowed, and it grows with the rate and the length of repayment. A $30,000 loan at 6.5% costs about $10,900 in interest over 10 years, but more than double that over 20. Enter your balance, rate, and term to see your total interest and total amount repaid.
Monthly payment
$464.43
Principal + interest
Total interest
$15,732
Over the loan
Total paid
$55,732
Principal + interest
Payoff time
10 yr
On schedule
Amortization schedule
Amortization schedule
| Year | Principal | Interest | Balance |
|---|---|---|---|
| 1 | $2,864 | $2,709 | $37,136 |
| 2 | $3,071 | $2,502 | $34,065 |
| 3 | $3,293 | $2,280 | $30,772 |
| 4 | $3,531 | $2,042 | $27,241 |
| 5 | $3,786 | $1,787 | $23,455 |
| 6 | $4,060 | $1,513 | $19,395 |
| 7 | $4,354 | $1,220 | $15,041 |
| 8 | $4,668 | $905 | $10,373 |
| 9 | $5,006 | $568 | $5,368 |
| 10 | $5,368 | $206 | $0 |
What drives your interest cost
Two things decide how much interest you pay: the rate and the time. A higher rate costs more every month, but a longer term is often the bigger factor — stretching repayment over more years means interest accrues on the balance for longer. Paying even a little extra, or choosing a shorter term you can afford, cuts the total noticeably. The calculator shows the difference.
How we calculate this
Every number on this page comes from the same fixed-rate amortization a loan servicer uses:
- Monthly payment. M = P·r ÷ (1 − (1 + r)⁻ⁿ), where P is your balance, r is the annual rate ÷ 12, and n is the number of months in the term.
- Total interest. the loan is simulated month by month: each payment covers that month's interest first, and the rest reduces principal. Summing the interest portions gives the total interest.
- Extra payments. any extra amount is applied to principal each month, so the loan reaches zero sooner. We simulate with and without it to show the months saved and interest avoided.
- Total paid & payoff time. total paid is principal plus all interest; payoff time is the month the balance reaches zero — earlier when you pay extra.
Assumptions
- A fixed interest rate held for the life of the loan — variable-rate loans reset and are not modeled here.
- Repayment starts now on the current balance; in-school interest accrual and capitalization are not included.
- Standard amortized repayment — income-driven plans that recalculate payments yearly are not modeled.
- Educational estimates, not financial advice — your servicer's figures govern.
Last reviewed: July 19, 2026
Frequently asked questions
Related tools
How is my student loan monthly payment calculated?+
Your payment comes from standard amortization: the loan balance, the interest rate, and the repayment term. The formula is M = P·r ÷ (1 − (1 + r)⁻ⁿ), where P is the balance, r is the monthly rate (annual rate ÷ 12), and n is the number of months. The standard federal plan is 10 years (120 payments). Enter your balance, rate, and term above to see the payment and total interest.
How can I pay off my student loans faster?+
Paying extra each month goes straight to principal, which shortens the loan and cuts total interest. Even a small extra amount adds up: on a $30,000 loan at 6.5%, an extra $150 a month can shave years off the term and save thousands in interest. Enter an extra payment above to see how much sooner you'd finish and how much interest you'd save. Make sure your servicer applies extra payments to principal, not to future bills.
What is the standard student loan repayment term?+
The standard federal repayment plan is 10 years (120 fixed monthly payments), and it's the default unless you choose another plan. Extended and income-driven plans stretch payments over 20–25 years, which lowers the monthly amount but raises total interest. This calculator lets you set any term so you can compare the standard 10-year plan against a longer one.
How much interest will I pay on my student loans?+
Total interest depends on your balance, rate, and how long you take to repay. On a $30,000 loan at 6.5% over 10 years you'd pay roughly $10,900 in interest; stretch it to 20 years and interest more than doubles even though the monthly payment drops. The calculator shows your total interest and total amount paid so you can see the real cost of a longer term.
Should I refinance or just pay extra on my student loans?+
Paying extra always helps and costs nothing, so it's the safe first move. Refinancing can lower your rate, but for federal loans it means giving up protections like income-driven plans and forgiveness — so weigh that carefully. Use this calculator to see what extra payments do at your current rate; if you're considering a new rate, compare it here and check our refinance calculator too.
Are these student loan figures exact?+
They're accurate for a fixed-rate loan repaid on schedule, which covers most federal and many private student loans. They don't model variable rates, in-school interest accrual, capitalization, deferment, or income-driven plans that recalculate payments each year. Use this for planning your standard repayment and extra-payment strategy, and confirm specifics with your loan servicer.
Estimates for planning only, not financial advice. Models fixed-rate amortized repayment; excludes in-school accrual, capitalization, and income-driven plans. Your servicer’s figures govern.