Student Loan Interest Calculator

To use this student loan interest calculator, follow these steps:

1. Enter your current loan balance. This is the total outstanding principal on the loan you want to analyze. If you have multiple loans, you can calculate each one separately or enter the combined balance with a weighted average interest rate.
2. Enter the annual interest rate. For federal loans, you can find your exact rate by logging into studentaid.gov and viewing your loan details under the My Aid section. For private loans, check your most recent billing statement or lender portal.
3. Select your desired loan term from the dropdown menu. The standard federal repayment term is 10 years, but extended and income-driven plans can stretch to 20 or 25 years.
4. Optionally, enter a custom monthly payment in the advanced settings if you want to override the calculated standard payment. This is useful for modeling income-driven plan payments or any non-standard amount.
5. Optionally, enter an extra monthly payment to see how additional principal payments reduce your total interest and accelerate your payoff date.

The calculator instantly displays your required monthly payment, total interest paid, total amount repaid, estimated payoff date, and interest savings from any extra payments. Experiment with different extra payment amounts to find a strategy that balances aggressive payoff with your monthly budget. Even an extra $50 or $100 per month can save thousands in interest over the life of the loan.

To find your federal loan details, visit studentaid.gov, sign in with your FSA ID, and navigate to My Aid, then View Loan Details. This page shows each loan, its servicer, interest rate, disbursement date, and current balance. For private loans, contact your lender directly or check their online portal for your current balance and rate.

A student loan interest calculator estimates how much interest you will pay on your student loans over the full repayment period and shows the impact of different repayment strategies. It helps you understand the true cost of borrowing for education and compare timelines for becoming debt-free.

Student loans fall into two broad categories: federal student loans and private student loans. Federal loans are issued by the U.S. Department of Education and carry fixed interest rates set by Congress each year. For the 2025-2026 academic year, federal undergraduate loan rates are approximately 6.5%, graduate loan rates are around 8%, and Parent PLUS loans are near 9%. Private student loans are issued by banks, credit unions, and online lenders. Their rates can be fixed or variable and are based on your credit score, ranging from as low as 4% for top-tier borrowers to 14% or more for those with limited credit history.

A critical distinction within federal loans is subsidized versus unsubsidized. Subsidized Direct Loans do not accrue interest while you are enrolled at least half-time or during deferment periods, because the government pays the interest on your behalf. Unsubsidized loans begin accruing interest from the day they are disbursed, even while you are still in school. If you do not pay the interest during school, it capitalizes (gets added to the principal) when repayment begins, increasing your total balance and the amount of interest you ultimately pay.

Federal borrowers have access to multiple repayment plan options. The Standard Repayment Plan spreads payments evenly over 10 years. The Graduated Repayment Plan starts with lower payments that increase every two years. Income-Driven Repayment (IDR) plans, including SAVE, IBR, PAYE, and ICR, calculate your payment as a percentage of your discretionary income and extend the term to 20 or 25 years, with any remaining balance forgiven at the end. While IDR plans lower your monthly obligation, they often result in significantly more total interest paid over the life of the loan.

Borrowers who pay student loan interest may also qualify for the student loan interest deduction on their federal tax return. This allows you to deduct up to $2,500 in student loan interest paid per year from your taxable income, even if you do not itemize deductions. The deduction phases out at higher income levels, making it most beneficial for early-career borrowers. Understanding all of these factors is essential for choosing the repayment strategy that minimizes your total cost while fitting your monthly budget.

Student loan monthly payments are calculated using the standard amortization formula:

M = L × [r(1 + r)n] / [(1 + r)n − 1]

Where each variable is defined in the table below:

The total interest paid over the life of the loan is:

Total Interest = (M × n) − L

Student loan interest actually accrues on a daily basis using the following formula:

Daily Interest = Outstanding Principal × (Annual Interest Rate / 365.25)

Each month, approximately 30 days of accrued interest is charged to your account. When you make your monthly payment, the accrued interest is paid first, and the remainder goes toward reducing the principal. This is why early payments are interest-heavy and later payments are principal-heavy. As your balance decreases, less interest accrues each day, and a larger share of each payment reduces the principal.

If you make extra payments, the additional amount goes directly toward principal reduction, which lowers the daily interest accrual going forward. This creates a compounding savings effect: each dollar of extra principal paid today saves you interest on that dollar for every remaining month of the loan. The earlier you make extra payments, the greater the cumulative interest savings.

Example 1 — $25,000 Balance (Typical Bachelor's Degree): A recent graduate has $25,000 in federal student loans at 5.5% interest on the standard 10-year repayment plan. The monthly payment is $271.57. Over 120 months, total payments equal $32,588, meaning $7,588 goes to interest. If this borrower makes an extra $75 per month ($346.57 total), the loan is paid off in approximately 87 months (7 years and 3 months), saving about $2,200 in interest. The student loan interest deduction could save an additional $400 to $600 in taxes during the first few years when interest payments are highest.

Example 2 — $50,000 Balance (Graduate Degree): A graduate student carries $50,000 in loans at 7.0% interest. On the standard 10-year plan, the monthly payment is $580.54, and total interest over 120 months is $19,665, for a total repayment of $69,665. If this borrower switches to a 20-year term, the monthly payment drops to $387.65, but total interest nearly doubles to $43,036, bringing total repayment to $93,036. If the borrower instead stays on the 10-year plan and adds $200 per month in extra payments ($780.54 total), the loan is paid off in about 75 months (6 years and 3 months), with total interest reduced to approximately $13,700. This saves nearly $6,000 compared to the standard plan and over $29,000 compared to the 20-year plan.

Example 3 — $100,000 Balance (Professional Degree): A law or medical school graduate has $100,000 in loans at 7.5% interest. On a standard 10-year plan, the monthly payment is $1,187, and total interest is $42,440, for total repayment of $142,440. Many borrowers at this debt level opt for an income-driven repayment plan. On a 25-year IDR plan with payments starting at approximately $600 per month and increasing with income, total interest can exceed $90,000, making total repayment over $190,000. However, if any balance remains after 20 to 25 years on an IDR plan, it is forgiven (though the forgiven amount may be taxable). Alternatively, if this borrower can manage $1,500 per month, the loan is paid off in about 84 months (7 years) with approximately $26,000 in total interest, saving over $16,000 compared to the standard plan. Borrowers in public service positions should also explore Public Service Loan Forgiveness (PSLF), which forgives remaining balances after 120 qualifying payments.