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Loan Amortization Calculator

A loan amortization calculator builds a month-by-month schedule that splits every payment into interest and principal. It also reports the fixed monthly payment and the total interest over the life of the loan.

By the Loansloth Editorial Team · Last updated 2026-09-16

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How this calculator works

An amortization schedule splits every payment into interest and principal. Early payments are mostly interest; later payments are mostly principal.

For each month:

  1. Interest = current balance * r, where r = annual rate / 12 / 100.
  2. Principal = monthly payment - interest.
  3. New balance = current balance - principal.

The fixed monthly payment comes from M = P * r * (1 + r)^n / ((1 + r)^n - 1). The final payment is adjusted so the balance lands exactly on zero.

With a 0% rate, every payment is pure principal and the balance falls in equal steps.

Frequently asked questions

What is an amortization schedule?
It is a table of every payment showing how much goes to interest, how much goes to principal, and the balance left after each payment.
Why is most of my early payment interest?
Interest is charged on the outstanding balance. At the start the balance is largest, so the interest portion is largest. As the balance falls, more of each payment goes to principal.
What happens on the final payment?
The last payment is adjusted so the remaining balance reaches exactly zero. It may be slightly smaller than the regular payment because of rounding in earlier months.
Does a 0% loan still amortize?
Yes. With no interest, the payment is the principal divided by the number of months, and every payment reduces the balance by the same amount.

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