Monthly Payment (Principal & Interest) Calculator

Inputs

How it works

Enter your loan amount, rate, and term. Optionally add a monthly extra principal payment and a start month.
Click Calculate to see your monthly principal-and-interest payment, totals, and a full amortization schedule.
Use Download CSV to export the schedule or Print for a clean report.

FAQs

We use the standard amortization formula: Payment = P × r × (1+r)^n / ((1+r)^n − 1), where P is loan amount, r is the monthly interest rate, and n is total payments.

No. This tool focuses on principal and interest only. Property taxes, homeowners insurance, PMI, HOA dues, and other fees should be added separately for a full monthly housing cost.

With a 0% rate, your monthly payment is simply the loan amount divided by the number of months. Our calculator switches to this linear payoff automatically to avoid divide-by-zero issues.

Extra principal reduces the outstanding balance faster, which lowers future interest charges and shortens the payoff time. You will usually save significant interest over the life of the loan.

To avoid overpaying on the last period, the tool caps the final payment to the remaining balance plus interest. That makes the last payment smaller than the regular monthly amount.

Calculations are performed in full precision; displayed values are rounded to 2 decimals. Internally we use a small tolerance to avoid negative balances caused by rounding drift.

How do you calculate the monthly payment?

Does this include taxes, insurance, or fees?

What happens if my interest rate is zero?

How do extra principal payments help?

Why does my final payment look smaller?

What rounding rules are used?

Related Calculators