Student loan calculator — estimate monthly student loan payment, total interest, and the impact of extra payments on payoff time.
Uses the same standard amortization formula servicers use for fixed-rate federal and private student loans.
Student loans use the same amortization math as a mortgage — but the term and rate combinations vary widely between federal subsidized, unsubsidized, PLUS, and private loans. This calculator estimates a standard repayment schedule and shows how much an extra monthly payment can shrink both the term and the total interest you'll pay.
Monthly payment M = P × r / (1 − (1 + r)^−n), where P is balance, r is monthly rate (APR ÷ 12), n is total payments (years × 12). Extra payments reduce the balance immediately each month, shortening n and the total interest.
A $35,000 loan at 6.5% on a 10-year standard plan: about $397/mo, total interest ≈ $12,700. Adding $100/mo extra cuts payoff to about 7 years 7 months and saves around $3,400 in interest.
Estimate the monthly payment, total interest, and total cost of a personal loan at any rate and term.
Estimate your monthly car payment with down payment, trade-in value, sales tax, and fees built in.
Compare two loan offers side by side — monthly payment, total interest, total cost including fees, and effective APR.
Calculate the true APR of a loan when origination fees, points, and other financed costs are included — the number that actually compares two offers.
Yes for standard fixed-rate repayment. Income-driven federal plans (SAVE, IBR, PAYE) use different formulas and aren't modeled here.
Most servicers default extra payments to advance the next due date. Log in or call to specifically request 'apply extra to principal'.
Compare your loan APR to a realistic investment return. Above ~6% APR, paying extra usually wins; below, investing may make more sense.
This calculator is for educational and estimation purposes only. It does not provide financial, mortgage, tax, investment, or legal advice. Actual rates, payments, taxes, fees, insurance costs, eligibility, and loan terms vary by lender, location, credit profile, and market conditions. Always compare official offers and consult a qualified professional before making financial decisions.
Last updated June 2026 · Prepared by the mCalculator Editorial Team