Student Loan Interest Calculator
See how much of your payment goes to interest vs principal each month.
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
Our Student Loan Interest Calculator helps you visualize exactly how your monthly payments are split between interest and principal. Understanding this breakdown is crucial for budgeting and strategizing repayment, especially with potential changes to federal student loan interest rates and repayment plans anticipated by 2026. This tool empowers you to see the true cost of borrowing over time.
This calculator uses a standard amortization formula to determine the interest and principal portions of each payment. The formula is P * (r * (1 + r)^n) / ((1 + r)^n – 1) for the monthly payment, where P is the principal loan amount, r is the monthly interest rate (annual rate / 12), and n is the total number of payments. We then calculate interest for a given month as the outstanding principal multiplied by the monthly interest rate, with the remainder of the payment going towards principal reduction.
Remember that interest rates can fluctuate, especially for variable-rate loans, so regularly re-evaluate your situation. Many federal student loan borrowers may be on income-driven repayment plans, which can significantly alter the interest vs. principal split, sometimes leading to negative amortization where your principal balance actually increases. Be aware that making extra payments directly to principal can dramatically reduce your overall interest paid and loan term.
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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