Loan Calculator: Monthly Payment, Total Interest and Schedule

  • Free
  • No sign-up
  • Runs in your browser
  • Version 1.0.0
  • Last updated 2026-10-07
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Enter the amount, the yearly interest rate and the term in months. You get the monthly payment, the total interest and a month-by-month schedule.

Everything you enter is processed in your browser and is never sent to a server.

How to use

  1. Type the loan amount, the annual interest rate in percent and the term in months.
  2. Pick a repayment method: equal payments, equal principal, or interest only with the principal due at the end.
  3. Read the first and last payment, the total interest and the total paid. Open the schedule to see each month.

Examples

10,000 at 5% for 12 months, equal payments
→ 856.07 a month, 272.90 total interest
The payment is the same every month, so the last payment is also 856.07.
24,000,000 at 6% for 24 months, equal principal
→ first 1,120,000, last 1,005,000, interest 1,500,000
Each month repays 1,000,000 of principal plus interest on the balance, so payments fall over time.
12,000,000 at 6% for 12 months, interest only
→ 60,000 a month, then 12,060,000 in the last month

How it works

For equal payments the monthly payment is P r / (1 - (1 + r)^-n), where P is the amount, r the monthly rate (annual rate divided by 12) and n the number of months. Each month the interest is the balance times r, and the rest of the payment reduces the balance. With a zero rate the payment is just P divided by n.

For equal principal each month repays P / n plus the interest on the remaining balance. For interest only each month pays the interest on the full amount, and the last month adds the whole principal.

Amounts are calculated without rounding and rounded only when shown, so the schedule balance reaches exactly zero. A lender that rounds every payment may differ from this by a few cents or won.

The tool is tested against the standard formula and against hand-calculated totals for each method.

Sources

Frequently asked questions

What is the difference between equal payments and equal principal?
With equal payments every month costs the same, and early payments are mostly interest. With equal principal you repay the same part of the balance each month, so the first payment is the highest and the total interest is lower.
Why is total interest lower with equal principal?
The balance falls faster, because more of the early payments go to principal. Interest is charged on the balance, so a lower balance means less interest.
Does this include fees, insurance or a variable rate?
No. It assumes one fixed rate for the whole term, interest charged monthly at one twelfth of the annual rate, and no fees. Real loans can differ, so use the lender's own figures for a decision.
How is the rate applied each month?
The annual rate is divided by 12 and applied to the remaining balance. This is the usual convention for monthly-payment loans, but some lenders count days instead.
Are my numbers sent anywhere?
No. All calculations run in your browser.
Version history
  • 1.0.0 — First release.

Last updated: