Loan Amortization Calculator
Use this tool to build a month-by-month amortization schedule. It splits every payment into interest and principal, and it reports the fixed monthly payment and the total interest over the loan's life.
Enter your numbers and press Calculate. Nothing you type leaves your browser.
How this calculator works
A schedule breaks each payment into two components, interest and principal. The interest share dominates early; the principal share dominates late.
Month by month:
- Interest = current balance * r, where r = annual rate / 12 / 100.
- Principal = monthly payment - interest.
- New balance = current balance - principal.
The level payment comes from M = P * r * (1 + r)^n / ((1 + r)^n - 1). We adjust the final installment so the balance lands on zero exactly.
At a 0% rate the whole payment is principal, and the balance drops in equal steps.
Common questions
What does an amortization schedule contain?
It is a row-by-row table of the loan, giving the interest share, the principal share and the outstanding balance after every payment.
Why does interest dominate the early payments?
Interest is computed on the outstanding balance, and that balance is at its peak early on, so the interest share is largest then. As the balance comes down, principal takes a bigger share of each payment.
What changes on the last payment?
We adjust the final installment so the balance closes at exactly zero. Rounding during earlier months can leave it a little smaller than a normal payment.
Does amortization still apply at 0%?
It does. At 0% interest the payment is simply principal divided by months, and every payment reduces the balance by an equal step.