Student Loan Calculator
Plan student loan repayment and see how extra payments cut interest.
About the Student Loan Calculator
Enter your loan balance, interest rate and repayment term to see the monthly payment and the total interest. Add an extra amount each month to see how much sooner the loan is cleared and how much interest you save.
US federal student loans default to a 10-year standard repayment plan with equal monthly payments, which is what this calculator models. Income-driven plans base payments on income instead; private loans follow their contract.
The formula
Payment = P × i ÷ (1 − (1 + i)^−n)
- P
- loan balance
- i
- monthly rate: yearly rate ÷ 12
- n
- number of monthly payments (years × 12)
Worked example
$35,000 at 6.39% over 10 years
- Monthly payment: $395.46
- Total interest over 120 payments: about $12,455
- Adding $100 a month clears it in 89 months and cuts interest to about $9,022
Things to keep in mind
- Assumes a fixed rate and no deferment or forbearance, during which interest may keep growing.
- Income-driven repayment and loan forgiveness are not modelled.
- Ask your servicer to apply extra payments to principal, not to future payments.
Questions people ask
Are federal loan rates fixed?
Yes, set each year for new loans and fixed for the life of the loan.
Can I deduct interest?
Up to $2,500 a year, subject to income limits (US).
Should I pay off student loans early?
Paying early earns a guaranteed return equal to the loan rate. Many people first build an emergency fund and capture any employer retirement match.