Student Loan Payoff Calculator

Q: How much do extra payments save on a student loan?

On a $35,000 loan at 5.5% over a 10-year term, an extra $50 per month cuts the loan short by about 18 months and saves roughly $1,672 in total interest.

Q: Will extra payments hurt loan forgiveness eligibility?

For federal loans on an income-driven repayment plan working toward forgiveness (like PSLF), paying extra doesn't help — forgiveness is based on time and qualifying payments, not balance, so extra payments there are typically wasted money. This calculator is meant for standard fixed repayment, not forgiveness-track federal loans.

Q: Should I pay off federal or private student loans first?

Generally, prioritize whichever loan has the higher interest rate, since that's where extra payments save the most. Private loans often carry higher rates than federal loans, but check your specific rates rather than assuming.

Q: Does an extra payment go entirely toward principal?

Most servicers apply extra payments to principal by default, but confirm — some require you to specifically direct the extra amount toward principal rather than the next due payment.

See exactly how much time and interest an extra monthly payment saves on your student loan — enter your loan details and an extra amount to compare.

Written by the Calculator Index team · Source: standard amortization formula (fixed-rate installment loan) · Last reviewed September 2026

New payoff time

—

Monthly payment

—

Months saved

—

Interest without extra payments

—

Interest with extra payments

—

Total interest saved

—

How extra payments shorten a student loan

Monthly payment = P × r / (1 − (1 + r)⁻ⁿ), where r = monthly rate, n = number of payments
Each extra dollar paid reduces principal immediately, lowering every future month's interest charge

On a standard fixed-repayment student loan, extra payments work the same way they do on any installment loan: the extra amount reduces principal directly, so every remaining month's interest — calculated on whatever balance is left — shrinks along with it. Over a typical 10-year student loan term, even a modest extra payment compounds into a meaningful reduction in total interest paid.

Worked example — $35,000 loan, 5.5% APR, 120-month term, $50 extra/month

Standard payment: $379.84/month, paid off in about 121 months, total interest ≈ $10,581.

With $50 extra every month: paid off in about 103 months (18 months early) — total interest drops to about $8,909, saving roughly $1,672.

When extra payments don't help — a federal loan forgiveness caveat

This calculator is built for a standard fixed-repayment loan, where the goal is minimizing total interest by paying it off faster. If you're on a federal income-driven repayment plan working toward loan forgiveness (such as Public Service Loan Forgiveness), the math is completely different: forgiveness is earned through a number of qualifying payments over time, not by reducing your balance. Paying extra in that situation typically doesn't help and may just be money you can't get back — check your specific forgiveness track before making extra payments on a federal loan.

Common mistakes when estimating student loan payoff

Applying this calculator to a forgiveness-track federal loan. Those work on a payment-count basis, not a balance-payoff basis — extra payments there don't accelerate forgiveness.
Paying extra on the lower-rate loan first when you have multiple loans. Prioritize the highest-rate balance to maximize interest savings.
Not confirming the extra payment is applied to principal. Some servicers apply it to the next due date instead unless you specify otherwise.

Frequently asked questions

How much do extra payments save on a student loan?

On a $35,000 loan at 5.5% over 10 years, an extra $50/month saves about $1,672 in interest and finishes about 18 months early.

Will extra payments hurt loan forgiveness eligibility?

Extra payments don't help on forgiveness-track federal plans like PSLF, since forgiveness is based on qualifying payment count, not balance.

Should I pay off federal or private student loans first?

Generally prioritize whichever loan has the higher rate — private loans often (but not always) carry higher rates than federal loans.

Does an extra payment go entirely toward principal?

Usually, but confirm with your servicer — some apply it to the next due payment unless you direct it to principal.

Related calculators

Note: Simplified estimate assuming a fixed-rate loan and extra payments applied fully to principal each month; does not apply to income-driven or forgiveness-track federal repayment plans. Not financial advice. Last reviewed: September 2026.