How to use the student loan calculator
- Choose what to find: your monthly payment on a set term, or the payment to be debt-free sooner.
- Enter your loan balance. For several loans, add the balances together.
- Enter the interest rate. With several loans, use the balance-weighted average: multiply each balance by its rate, add the results, and divide by the total balance.
- For your payment, enter the repayment term (10 years is the default) and, optionally, an extra payment each month.
- For a goal, enter the number of years you want to be debt-free in.
How the payment is calculated
Fixed-payment student loan plans use standard amortization, the same math as a car loan or mortgage:
Interest accrues on the balance each month and the payment covers it first. An extra payment goes to principal, so later months carry less interest and the loan ends sooner. Federal servicers apply any payment to unpaid interest first and then principal, and you can ask them to put any amount above the required payment toward principal.
Worked example
The defaults are a $30,000 balance at 6.5% over 10 years:
- Monthly rate: 0.065 ÷ 12 = 0.0054167, and n = 120
- (1.0054167)^120 = 1.91218
- Payment: 30,000 × 0.0054167 × 1.91218 ÷ 0.91218 = $340.64
- First month: $162.50 of interest, $178.14 toward the balance
- Over 10 years you pay $40,877.27, of which $10,877.27 is interest
To be debt-free in 5 years instead, the payment is $586.98: $246.34 more a month, but total interest falls to $5,219.07, saving $5,658.21. Adding just $100 a month to the 10-year payment ($440.64 in all) clears the loan in 7 years 2 months and saves $3,346.98.
Extra payments and longer terms compared
The same $30,000 at 6.5%:
| Plan | Monthly payment | Paid off in | Total interest |
|---|---|---|---|
| 25 years | $202.56 | 25 years | $30,768.64 |
| 20 years | $223.67 | 20 years | $23,681.27 |
| 10 years | $340.64 | 10 years | $10,877.27 |
| 10 years + $50 | $390.64 | 8 years 4 months | $8,892.17 |
| 10 years + $100 | $440.64 | 7 years 2 months | $7,530.29 |
| 10 years + $200 | $540.64 | 5 years 7 months | $5,777.86 |
Stretching to 25 years cuts the payment by about $138 but almost triples the interest.
US federal repayment plans in 2026
The federal rules changed under the 2025 budget reconciliation law (P.L. 119-21). For loans made before July 1, 2026, the original Standard plan (fixed payments over 10 years), Graduated and Extended plans remain. For loans first disbursed on or after July 1, 2026, borrowers choose between a Tiered Standard plan, with fixed payments over 10 to 25 years depending on the balance, and the income-driven Repayment Assistance Plan (RAP), which sets payments from 1% to 10% of income for up to 30 years. Source: Congressional Research Service, "Available Student Loan Repayment Plans Following the FY2025 Budget Reconciliation Law" (IG10093). New undergraduate Direct Loans disbursed from July 1, 2026 to June 30, 2027 carry a fixed 6.52% rate (Federal Student Aid announcement GENERAL-26-33).
This calculator models fixed-payment plans only. Income-driven payments depend on your income and family size and change each year, so check them with your servicer or the official loan simulator at studentaid.gov. Private student loans follow the lender's own terms.
Frequently asked questions
Should I pay off student loans early or invest?
Compare the loan rate with what you could reasonably earn after tax. Paying off a 6.5% loan is a guaranteed 6.5% return, which is hard to beat safely. Many people first grab any employer retirement match, build an emergency fund, and then add extra to their highest-rate loans.
Does an extra payment lower my required payment?
No. On a fixed plan the required payment stays the same and the loan ends sooner. If you pay ahead, federal servicers may advance your due date; tell them to apply the extra to principal instead so it cuts interest.
How do I combine several student loans?
Add the balances and use a weighted average rate. With $20,000 at 6% and $10,000 at 7.5%, the average is (20,000 × 6 + 10,000 × 7.5) ÷ 30,000 = 6.5%. A federal Direct Consolidation Loan uses a similar weighted average, rounded up to the nearest one-eighth of a percent.
Is student loan interest tax-deductible?
In the US you can deduct the lesser of $2,500 or the student loan interest you actually paid in the year, but the deduction phases out at higher incomes. See IRS Topic no. 456 for the current income limits before you count on it.
Related calculators
- Debt Payoff Calculator — Compare the snowball and avalanche methods across all your debts and see your debt-free date.
- Payment Calculator — Monthly payment for a loan with a fixed term, or how long a fixed monthly payment takes to clear it.
- Amortization Calculator — Loan amortization schedule by year, with the payoff date and what an extra monthly payment saves.
- Debt-to-Income Ratio Calculator — Your front-end and back-end debt-to-income ratios, compared with common mortgage lender limits.
Results are estimates for educational purposes and are not financial, tax or legal advice. See our disclaimer.