Amortization Calculator
See every scheduled payment: how much goes to principal, how much to interest, and what balance is left after each month.
What amortization means
On a fixed-rate mortgage, your monthly principal-and-interest payment stays level, but what happens inside that payment changes every month. Early payments are mostly interest because the lender is charging on a high balance. Later payments are mostly principal because the balance is smaller.
The schedule is the row-by-row record of that process — payment date, interest, principal, and remaining balance.
Reading the payment-by-payment table
- Scheduled payment — monthly P&I (plus any extra principal you enter)
- Interest paid — beginning balance × monthly rate
- Principal paid — scheduled payment minus interest
- Ending balance — what you still owe after the payment
The balance chart shows how principal declines month by month. When the orange line appears, it tracks cumulative interest paid — handy for seeing borrowing cost at any point in the term.
Extra principal in the schedule
Add a monthly extra principal amount to see fewer rows in the table and a faster balance decline. Each extra dollar reduces the balance that future interest is charged on. The extra payment calculator summarizes time and interest saved; this tool shows the payment-by-payment effect.
Tell your servicer in writing that additional amounts should apply to principal, not future installments.
Final payment and rounding
Calculations use full precision; values round only at display. The engine adjusts the last payment so the balance ends at zero. Your servicer’s schedule may differ by a few cents per payment depending on rounding conventions. See methodology for details.
When this tool is useful
- Seeing how much interest you pay in the first few years of a loan
- Planning extra principal and checking the shortened payoff path
- Comparing how a different rate or term changes total interest
- Seeing why refinancing or recasting changes your monthly bill