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How to Calculate a Loan Payment

The amortization formula behind every fixed monthly payment, explained plainly.

5 min read

Step by step

  1. Convert the annual rate to a monthly rate: rate ÷ 100 ÷ 12.
  2. Count the total number of monthly payments (years × 12).
  3. Payment = principal × r ÷ (1 − (1 + r)^−n).
  4. Example: $20,000 at 5% over 5 years is about $377.42 per month.

Key takeaway: Interest is charged on the remaining balance, so it shrinks every month.

Do it automatically

Monthly payment, total interest and a full amortization schedule.

Open the Loan Payment Calculator