Student Loan Calculator
The arithmetic of a student loan on a standard repayment schedule: the monthly payment, total interest, and what an extra payment saves. Federal program rules change — the page says so, plainly.
The standard plan, and the value of paying past it
The federal standard plan amortizes a student loan over 10 years — the schedule this calculator reproduces for the balance and rate you enter. The interesting question is the second one: what does an extra $50 or $100 a month actually buy? On student loans the answer is measured in years of payments deleted and thousands of interest avoided.
Payment = balance × r ÷ (1 − (1 + r)−120) on the standard 10-year schedule, r = rate ÷ 12
Example: $35,000 at 5.5%: the standard payment is $379.77 and the interest totals about $10,572. Add $100 a month and the loan ends roughly 2 years 4 months early, saving around $2,900 of interest. Run your own balance above.
Programs change. Federal repayment plans, income-driven options, forgiveness programs and interest policies are set by legislation and rulemaking and have changed repeatedly. This page does arithmetic on your balance and rate; it is not a guide to current federal programs — studentaid.gov and your servicer are.
How this is calculated
Standard level-payment amortization over the term you enter (10 years default), nominal rate ÷ 12, payments at month end. The extra payment is added to principal monthly and the schedule is re-simulated month by month, so the payoff time and interest figures are exact for the inputs — not estimates. Private loans follow the same arithmetic; federal program features (IDR, PSLF, deferment) are deliberately not modeled.
Frequently asked questions
Should I pay extra on student loans or save instead?
Depends on the rate and your safety net: an emergency fund and any employer retirement match come first for most people. After that, extra payments earn a guaranteed return equal to the loan's rate.
Does paying extra hurt Public Service Loan Forgiveness?
It can: PSLF forgives what remains after 120 qualifying payments, so extra payments shrink the amount forgiven. If you are on a genuine PSLF path, the arithmetic inverts — check your specific case before paying extra.
Why is my balance growing on an income-driven plan?
If the IDR payment is below the monthly interest, the balance rises (rules on interest subsidies have changed by plan and over time). This calculator's fixed-payment simulation shows the contrasting path where the payment always exceeds interest.
Can I refinance a federal loan privately?
Yes, but it permanently converts the loan to private — surrendering federal options like income-driven plans and forgiveness. Lower rate, fewer protections: the trade should be made awake, not by default.
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