Free Student Loan Calculator
How it works
Enter your loan balance, interest rate, and repayment term to get your standard monthly payment, total interest, and payoff time. Add an optional extra monthly payment and the calculator simulates your balance month by month to show your new payoff date and exactly how much interest you would save.
Student Loan Calculator
Your monthly payment, total interest, and how extra payments shrink both.
1 Your loan
2 Repayment plan
3 Calculate your payoff
🎓 Your repayment plan
The formula
The standard monthly payment uses the loan formula with monthly rate r = APR ÷ 100 ÷ 12 and n = years × 12: M = P × r × (1 + r)^n ÷ ((1 + r)^n − 1) (or P ÷ n when the rate is 0%). Total interest on the standard plan is M × n − balance. With an extra payment, there is no shortcut formula, so the calculator simulates month by month: each month it adds interest (balance × r), subtracts your payment plus the extra, and repeats until the balance reaches zero — counting the months and total interest as it goes.
Everyday uses
- Choosing a repayment term: see the true interest cost difference between a 10-year and a 20-year plan before you switch.
- Extra-payment motivation: find out what a spare $75 a month actually saves over the life of the loan.
- Refinance sanity check: run a refinanced rate and term here first to see whether the new plan really beats the old one.
- Debt-free date planning: work out exactly which month you will be done, and what it takes to pull that date closer.
Frequently asked questions
Is there a penalty for paying extra on student loans?
Federal student loans have no prepayment penalty, and most private loans do not either. Just tell your servicer to apply extra payments to the principal of your highest-rate loan, not as an early payment of next month’s bill.
Why does a small extra payment save so much interest?
Interest is charged on your remaining balance every month. Every extra dollar lowers the balance sooner, so every following month is charged interest on a smaller amount — the savings compound in your favor for the rest of the loan.
Should I pick a shorter term or just pay extra on a longer term?
A shorter term forces a higher payment but usually comes with a lower rate. Paying extra on a longer term gives you flexibility in tight months. Run both here: if the totals are close, the flexible option is often the safer choice.