Student Loan Calculator
Estimate the monthly payment, total interest, and payoff time on a student loan. Add an extra monthly payment to see how much faster you could be debt-free and how much interest you would save.
Model a student loan
Total amount borrowed, up to $10,000,000.
Use a rate from 0% through 40%.
Common student loan repayment terms.
Paying this amount pays off the loan in 120 months (10 years), including $9,967.38 in interest.
- Total interest
- $9,967.38
- Total paid
- $39,967.38
- Payoff time
- 120 months (10 years)
What if you pay more each month?
How a student loan payment is calculated
This calculator uses the standard fixed-rate, level-payment amortization formula. Each month, part of the payment covers interest on the remaining balance and the rest reduces principal. As the balance shrinks, more of each payment goes toward principal.
M = P × r(1 + r)n / ((1 + r)n − 1)- M
- Monthly payment
- P
- Loan balance (principal)
- r
- Monthly interest rate (annual rate ÷ 12)
- n
- Number of monthly payments (repayment term)
An optional extra monthly payment is applied directly to the remaining principal on top of the required payment. Because future interest is charged only on the remaining balance, consistently paying extra reduces both the total interest paid and the number of months needed to clear the loan.
$30,000 loan at 6% for 120 months
A $30,000 student loan at a 6% fixed annual interest rate with a 120-month (10-year) term produces an estimated monthly payment of $333.06. Over the full term, total interest comes to $9,967.38, for a total amount paid of $39,967.38. Adding $50 a month clears the loan in 100 months instead of 120 and cuts total interest to $8,163.44.
This is an educational estimate. Actual loans depend on the loan servicer, your repayment plan, capitalized interest, and other terms not modeled here.
What this calculator assumes
- The interest rate is fixed for the entire repayment term.
- No fees, capitalized interest, or interest subsidies are modeled.
- Any extra monthly payment is applied entirely to principal.
- Payments are made monthly, with interest compounding monthly.
- Money values are rounded to the nearest cent for display.
Student loan FAQ
Does paying extra on a student loan help?
Yes. Extra payments reduce the principal balance immediately, so every later payment accrues less interest. Even a modest recurring extra payment can shorten repayment by months or years and meaningfully cut total interest, especially earlier in the loan.
Does this model income-driven repayment plans?
No. This calculator models a standard fixed-rate, fixed-term repayment schedule with level monthly payments. It does not model income-driven plans, forgiveness programs, variable rates, deferment, or interest that capitalizes after a grace period.
Sources and review notes
Methodology last checked Jul 14, 2026. Formula implementation is covered by deterministic unit tests. No financial professional review is claimed yet.