Student Loan Calculator
Estimate your student loan monthly payment and total interest on a standard repayment plan. Enter your balance, rate, and term.
| Year | Principal | Interest | Balance |
|---|---|---|---|
| 1 | $2,258 | $1,739 | $27,742 |
| 2 | $2,397 | $1,599 | $25,344 |
| 3 | $2,545 | $1,451 | $22,799 |
| 4 | $2,702 | $1,294 | $20,097 |
| 5 | $2,869 | $1,128 | $17,228 |
| 6 | $3,046 | $951 | $14,182 |
| 7 | $3,234 | $763 | $10,948 |
| 8 | $3,433 | $564 | $7,515 |
| 9 | $3,645 | $352 | $3,870 |
| 10 | $3,870 | $127 | $0 |
Assumes a fixed rate and equal monthly payments. Excludes fees unless included in the rate.
How to use this calculator
Enter three values to get a complete repayment picture:
- Loan balance — your current total outstanding balance across all loans you want to model (or a single loan's balance)
- Interest rate — the annual interest rate on the loan; for multiple loans at different rates, run the calculator separately or use a weighted average
- Term — the repayment period in years; 10 years is the federal standard plan, but you can model longer or shorter terms
You'll see your monthly payment, total interest paid over the life of the loan, total repaid, and a year-by-year breakdown of principal, interest, and remaining balance. Try changing the term to 5 or 7 years to see how much interest you save by paying off faster.
How student loan repayment works
The standard repayment plan for federal student loans is a fully amortizing fixed-payment plan over 10 years (120 equal payments). Each payment covers all interest that accrued since the last payment, plus some principal. Because the balance is largest at the start, the early payments are mostly interest. As principal falls, each payment covers less interest and more principal — until the final payment eliminates the remaining balance.
Beyond the standard plan, federal borrowers have access to:
- Extended repayment — spreads payments over up to 25 years, lowering the monthly amount but substantially increasing total interest
- Graduated repayment — starts with lower payments that increase every two years, intended for borrowers expecting income growth
- Income-driven repayment (IDR) — caps payments at a share of discretionary income; remaining balances may be forgiven after 20–25 years
Private student loans typically follow a standard amortizing structure but don't offer income-driven plans or federal forgiveness programs.
Worked example — step by step
Suppose you have a $30,000 balance at 6% annual interest on the 10-year standard plan:
- Monthly rate: 6% ÷ 12 = 0.5%
- Monthly payment: $30,000 × [0.005 × (1.005)¹²⁰] ÷ [(1.005)¹²⁰ − 1] ≈ $333/month
- Total paid: $333 × 120 = $39,960
- Total interest: $39,960 − $30,000 = $9,960
In month 1: interest = $30,000 × 0.5% = $150; principal = $333 − $150 = $183; new balance = $29,817.
In month 120: interest ≈ $1.65; principal ≈ $331.35; balance = $0.
Now compare paying it off in 5 years: the payment rises to about $580/month, but total interest drops to roughly $4,800 — saving over $5,000 compared to the 10-year plan. If your budget allows the higher payment, the shorter term is almost always financially advantageous.
Alternatively, on the 10-year plan, adding just $100/month to principal reduces the payoff to roughly 7.5 years and cuts total interest to around $7,200.
How to interpret your result
Your monthly payment is the baseline to check against your post-graduation budget. A widely cited guideline is to keep total student loan payments below 10–15% of gross monthly income. If the standard payment exceeds that, an income-driven plan may be appropriate while your income grows.
The total interest figure reveals the true cost of financing your education. On a 10-year plan, total interest on $30,000 at 6% is about $10,000 — roughly a third of the original balance. Extending to 20 years at the same rate would push total interest above $21,000. This comparison underscores the importance of choosing the shortest term you can comfortably afford.
The year-by-year schedule shows when the balance drops below key thresholds. If you're planning to refinance or consolidate in a few years, this tells you what balance to expect at that time.
Common mistakes to avoid
- Choosing a long repayment plan without calculating the true cost. Extending from 10 to 25 years dramatically lowers the monthly payment, but the total interest can easily exceed the original loan amount. Always compare the total paid, not just the monthly obligation.
- Ignoring interest that accrued during school. On unsubsidized loans, interest accumulates from disbursement. If not paid before repayment begins, it capitalizes onto the principal — meaning you start repayment with a balance higher than what you borrowed. This calculator uses your current balance, so make sure you enter the actual balance after any capitalization, not just the original disbursed amount.
- Refinancing federal loans without understanding the trade-offs. Refinancing federal loans into a private loan can lock in a lower rate but permanently eliminates access to federal income-driven plans, forgiveness programs, and deferment options. This trade-off is not trivial, especially if your income is uncertain.
- Not directing extra payments to the principal. When you send extra money, specify that it should be applied to principal rather than being held as a future payment credit. Some loan servicers will apply extra funds to future payments (reducing next month's bill) rather than to principal, which does not reduce the balance the same way.
- Missing the student loan interest tax deduction. If your income falls within the eligible range, you may deduct up to $2,500 of student loan interest annually — reducing your taxable income even without itemizing deductions. Check IRS Publication 970 for current limits.
The formula
Payment = P × [ r(1 + r)n ] ÷ [ (1 + r)n − 1 ]
Where: P = loan balance, r = monthly interest rate (annual rate ÷ 12), n = total monthly payments (years × 12).
Interest for any period = remaining balance × r. Principal = Payment − Interest.
How we calculate this
Monthly payment is computed using the standard fixed-rate amortization formula: Payment = P × [r(1+r)ⁿ] ÷ [(1+r)ⁿ − 1], where P is the loan balance, r is the monthly interest rate (annual rate ÷ 12), and n is the total number of monthly payments (years × 12). Total interest equals all payments minus the original balance. The year-by-year breakdown applies the formula period by period to show the declining balance and shifting principal/interest split. Income-driven repayment plans, capitalized interest from school periods, and loan forgiveness programs are not modeled.
Sources
Frequently asked questions
How are student loan payments calculated?
On the standard repayment plan, student loans are fully amortized: each equal monthly payment covers the interest that has accrued on the remaining balance, plus some principal. Early payments go mostly to interest; later payments go mostly to principal. By the final payment, the balance reaches zero. The formula is the same standard amortization calculation used for other fixed-rate loans.
What is the standard repayment term for federal student loans?
Federal student loans default to a 10-year (120-month) standard repayment plan after the grace period ends. Extended plans can stretch this to 25 years, and income-driven repayment (IDR) plans set payments as a percentage of your discretionary income with forgiveness after 20–25 years. Longer plans lower monthly payments but significantly increase total interest paid.
Should I pay extra on my student loans?
Paying more than the minimum reduces principal faster and cuts total interest, and federal student loans carry no prepayment penalty. If you have multiple loans at different rates, target extra payments toward the highest-rate loan first (the 'avalanche' method) to minimize total interest. Even modest overpayments on a 10-year balance can save thousands.
Does this calculator cover income-driven repayment plans?
No — this calculator estimates standard fixed amortization. Income-driven repayment (IDR) plans such as SAVE, PAYE, and IBR set your payment as a percentage of discretionary income, which varies with your income and family size. The federal student aid website (studentaid.gov) has tools specifically for estimating IDR payments.
What is the difference between subsidized and unsubsidized federal loans?
With subsidized loans, the government pays the interest while you're in school at least half-time, during the grace period, and during deferment. With unsubsidized loans, interest accrues from the moment the loan is disbursed — including during school and grace periods. If you don't pay that accrued interest before repayment begins, it is capitalized (added to the principal), increasing the balance on which future interest accrues.
What happens to unpaid interest during school (interest capitalization)?
On unsubsidized loans, interest accrues while you're in school. If you don't pay it before entering repayment, the accrued interest is capitalized — added to your principal balance. This means you then owe interest on a larger balance, which increases both your monthly payment and total cost. Paying even small amounts during school can prevent significant capitalization.
Is student loan interest tax-deductible?
You may be able to deduct up to $2,500 of student loan interest per year from your taxable income, subject to income limits that the IRS adjusts periodically. This deduction is taken as an above-the-line adjustment, meaning you don't need to itemize to claim it. Check IRS Publication 970 or a current IRS source for the latest income phase-out ranges.
Should I refinance my student loans?
Refinancing can make sense if you qualify for a significantly lower rate, especially on high-rate private loans. However, refinancing federal loans into a private loan permanently eliminates federal protections such as income-driven repayment, forgiveness programs, and deferment options. Weigh those benefits against the potential rate savings before refinancing federal loans.