Student loan repayment calculator
Enter your loan balance, rate, and current monthly payment to see your real payoff time and total interest — plus how much a small extra payment each month would save.
Payoff time (current payment)
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Total interest (current payment)
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Time saved with extra payment
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Interest saved with extra payment
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Last updated: September 2026 · Verified by Hugo Cardozo.
How this calculator works
Each month, interest accrues on the remaining balance at your rate, then your payment covers that interest first with the rest going to principal. That's a standard amortizing loan — the same math behind a mortgage or car loan, just usually with a shorter term and a higher rate than a mortgage.
Worked example
A $30,000 balance at 5.5% with a $320 monthly payment pays off in about 123 months (a little over 10 years) and costs about $9,300 in total interest. Adding just $50/month extra — a $370 total payment — cuts that to about 102 months and roughly $7,600 in interest, saving about 21 months and $1,700, just from one modest change.
Why extra payments matter more early in the loan
Extra payments made early in the loan avoid the most future interest, because they shrink the balance that interest gets charged on for the entire remaining term. The same extra payment made in the loan's final year barely matters, since there's so little remaining life left for that interest to compound over.
Frequently asked questions
Does this account for income-driven repayment plans?
No — this assumes a fixed, standard amortizing payment. Income-driven plans tie your payment to your income and can result in a very different total cost, including potential loan forgiveness after a set number of years on some federal plans.
Should extra payments go to student loans or into investing?
It depends on your rate. Paying extra on loans above roughly 6-7% is often preferable to investing, since that return is essentially guaranteed; at lower rates, especially federal loans with borrower protections, many people choose to invest instead — there's no single right answer for every rate and situation.
Do extra payments automatically go to principal?
Not always — some servicers apply extra payments to future scheduled payments by default instead of the current principal. Check with your servicer that extra payments are specifically marked to reduce principal, or the time and interest savings shown here won't actually happen.
📘 Related guide
Read the full guide: "Student Loan Repayment Strategies That Actually Save Money".
Student Loan Repayment Strategies