Student Loan Interest Calculator
See how much of your payment goes to interest vs principal each month.
By Konstantin Iakovlev · Updated April 2026 · Source: FSA
Daily Interest
$5.27
Payoff Time
9.4 years
Total Interest
$9,835.30
Payment Allocation
| Monthly Interest | $160.42 |
| To Principal | $239.58 |
| % Going to Interest | 40.1% |
| Payoff Date | 113 months (9.4 yrs) |
Use the Student Loan Interest Calculator above to calculate your results. Enter your values and see instant results — all calculations run in your browser.
Disclaimer: This calculator is for informational purposes only and does not constitute tax, financial, or legal advice. Results are estimates based on the information you provide and current rates. Always consult a qualified tax professional or financial advisor for advice specific to your situation.
How It Works
Every loan payment you make splits in two: part covers interest, part chips away at principal. Seeing that division clearly is the foundation of any repayment strategy and a realistic budget, and it matters all the more as federal interest rates and repayment plans face possible changes by 2026. Watching the breakdown month by month reveals what borrowing actually costs you over time.
The math behind the breakdown is standard amortization. The monthly payment comes from P * (r * (1 + r)^n) / ((1 + r)^n – 1), where P is the principal loan amount, r is the monthly interest rate (annual rate / 12), and n is the total number of payments. For any given month, interest equals the outstanding principal times the monthly interest rate, and whatever is left of the payment reduces the principal.
Rates shift, particularly on variable-rate loans, so it is worth revisiting your numbers periodically. Borrowers on income-driven repayment plans see an especially different picture, since a low capped payment can tilt heavily toward interest and even trigger negative amortization, where the balance climbs instead of falling. Directing extra money straight at principal works in the opposite direction, cutting both your total interest and the length of the loan.
Example: Understanding Your Monthly Payment on a New Federal Loan in 2026
- 1 Imagine you take out a new unsubsidized federal student loan in 2026 for $30,000 with a fixed interest rate of 7.5% (a plausible rate based on current trends and projections for 2026, though actual rates may vary) and a standard 10-year repayment plan.
- 2 Using our calculator, we input a loan amount of $30,000, an annual interest rate of 7.5%, and a loan term of 120 months (10 years). The calculator determines your monthly payment to be approximately $358.53. For the first month, the interest due is $30,000 * (0.075 / 12) = $187.50.
- 3 In that initial month, $187.50 of your $358.53 payment goes towards interest, and the remaining $171.03 goes towards reducing your principal balance.
- 4 This example clearly shows that a significant portion of your early payments goes towards interest. As you continue to make payments and your principal balance decreases, a larger share of each subsequent payment will be allocated to principal, accelerating your debt repayment.
Source: FSA · Last updated: April 2026
Frequently Asked Questions
How much student loan interest do I pay each month?
Does paying extra on student loans reduce interest?
Is student loan interest simple or compound?
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