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Simple Calculators

Student Loan Calculator

Calculate monthly payments, compare repayment plans, and estimate income-driven payments

Student Loan Calculator
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2026–27 undergrad Direct Loans: 6.52%

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Used to estimate income-driven repayment (IDR)

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Quick summary

A student loan calculator computes your monthly payment for standard repayment plans (10–30 years) and helps you compare how much total interest you'll pay at different term lengths. It can also estimate income-driven repayment (IDR) payments based on your income.

Reviewed by Simple Calculators TeamLast reviewed

For planning only — not financial or tax advice. Results are estimates based on your inputs and the stated assumptions. Confirm important decisions with a qualified professional.

How to use this calculator

  1. Enter the inputs requested by the calculator.
  2. Choose the units or options that match your situation and review the assumptions.
  3. Run or update the calculation to see the result.
  4. Review the result, breakdown, and formulas shown on the page.
  5. Check the inputs, units, dates, and limitations before saving or sharing the result.

Student Loan Payment Formula

Monthly Payment (Standard Amortization)

M=P⋅r(1+r)n(1+r)n−1M = P \cdot \frac{r(1+r)^n}{(1+r)^n - 1}
P
Loan principal (balance)
r
Monthly interest rate (APR ÷ 12)
n
Number of monthly payments (years × 12)

Worked example

$30,000 at 6.54% for 10 years

Given
P = $30,000
r = 0.545%/month
n = 120 payments
Calculation
M=30,000⋅0.00545×(1.00545)120(1.00545)120−1M = 30{,}000 \cdot \frac{0.00545 \times (1.00545)^{120}}{(1.00545)^{120} - 1}
Result
≈ $339/month

Frequently asked questions

What is the federal student loan interest rate?

Federal Direct Loan interest rates are set by Congress each year and fixed for the life of the loan. For 2024–25: Undergrad Direct Subsidized/Unsubsidized = 6.53%, Graduate Direct Unsubsidized = 8.08%, Direct PLUS = 9.08%. Rates vary annually — check studentaid.gov for current rates.

What is income-driven repayment (IDR)?

IDR plans cap monthly payments at a percentage of your discretionary income. The SAVE plan (Saving on a Valuable Education) caps payments at 5% of discretionary income for undergrad loans and 10% for graduate loans, with forgiveness after 20–25 years. PAYE and IBR are alternatives. Contact your servicer or visit studentaid.gov for eligibility.

Should I pay off student loans or invest?

It depends on your interest rate. If your loan rate is below ~6%, investing in broad index funds (historically averaging ~7–10% annually) may yield better long-term returns. If your rate is above 7–8%, paying off the loan is a guaranteed return equal to that rate. Always capture any employer 401(k) match first — that's a 50–100% instant return.

What happens if I miss a student loan payment?

Federal student loans enter delinquency after one missed payment. After 90 days delinquent, the delinquency is reported to credit bureaus. After 270 days (about 9 months), loans go into default, triggering wage garnishment, tax refund seizure, and loss of eligibility for additional federal aid. Contact your servicer immediately if you're struggling — IDR or deferment options may be available.

Key terms

Subsidized Loan
A federal loan where the government pays interest while you're in school at least half-time, during grace periods, and deferment.
Unsubsidized Loan
A federal loan where interest accrues from disbursement — including while you're still in school.
Income-Driven Repayment (IDR)
Federal repayment plans that cap monthly payments at a percentage of discretionary income, with forgiveness after 20–25 years.
Grace Period
A 6-month window after graduation before federal loan repayment begins.

Methodology, sources & limitations

This page shows the formula, assumptions, and limitations used for this estimate. Rates, thresholds, and other time-sensitive inputs can change, so verify them against the relevant official source before relying on a result.

For our review approach and the primary sources we consult, see the methodology and source policy. If you spot an outdated figure or formula, please contact us with a correction.