Watcharu Finance

Student Loan Calculator

Student loans are simple fixed-rate installment loans, but paying a bit extra each month can erase years of interest. Enter your loan to see both paths.

$340.64 / month

Total interest (standard)
$10,877
Standard payoff
10.0 years
Sooner with extra payments
2 yr 10 mo
Interest saved
$3,347
On schedule vs With extra over YearOn schedule ends near $0 at 10; With extra ends near $513 at 7.$0$8k$15k$23k$30k0246810Year
On schedule With extra

How it works

The standard amortisation formula sets the fixed monthly payment. Extra monthly payments or a one-time lump sum are applied straight to principal, re-amortising the loan to show the new payoff date and interest saved.

Explain it to a kid

Going to college often costs more than a family has saved up, so many students borrow money to help pay for it and pay it back after they graduate and start working — a little each month, for years. The less you borrow, and the more extra you pay when you can, the less it ends up costing in the long run.

Frequently asked questions

How is a student loan payment calculated?
Federal and private student loans on a standard repayment plan use the same fixed-rate amortization formula as any installment loan: a level monthly payment that pays off the balance, plus all the interest it accrues, by the end of the term.
What's the standard repayment term for federal student loans?
The Standard Repayment Plan for federal loans is 10 years (120 months), though other federal plans stretch payments over up to 25 years for a lower monthly payment at the cost of more total interest. This calculator lets you enter any term to match your actual plan.
Does this cover income-driven repayment plans?
No — income-driven plans (like SAVE, IBR, or PAYE) set your payment as a percentage of income rather than a fixed amortization schedule, and their rules change periodically. This calculator models a standard fixed-payment loan; check studentaid.gov for income-driven options.
How much does an extra payment really save on a student loan?
Because student loan interest is calculated on the outstanding balance, any extra payment applied to principal skips all the future interest that balance would have accrued — even a modest recurring extra amount can cut years off a 10-year term.

Learn more: Student loan types and repayment plans — Subsidized vs. unsubsidized loans, what the grace period and capitalized interest actually do to your balance, standard vs. income-driven repayment, PSLF, and when consolidating a loan helps or hurts.

Related calculators

All calculators