Loan amortization calculator

What amortization actually is

A fixed-rate loan with equal monthly payments is "amortized": every payment covers the interest on the outstanding balance first, and whatever's left chips away at the principal. Early on, almost all of the payment is interest. Near the end, almost all of it is principal. The chart above is the visual shorthand for that shift: the brown slice (interest) is fat at the start and skinny at the end, and the teal slice (principal) does the opposite.

Why early extra payments save so much

Interest is charged on the outstanding balance, so a euro of extra principal in month one stops earning interest for the lender for the entire remaining life of the loan. The same euro paid in the last year barely saves anything. That's why a relatively small extra monthly payment, kept up over the years, can shave several years off a 25 or 30 year mortgage and erase tens of thousands of euros of interest. Try setting the extra payment to 100 or 200 EUR and watch the payoff date and the "interest saved" line move.

What this calculator doesn't include

This tool models the loan and only the loan. It assumes a fixed interest rate for the entire term, which is a reasonable proxy for a European fixed-rate mortgage but not for a variable-rate one. It does not include property taxes, building insurance, mortgage life insurance, origination fees, notary costs, or any of the other line items on a real loan offer. Treat the monthly payment as the principal + interest portion of a bigger bill, not the total bill. Reference: Amortization calculator on Wikipedia (retrieved 2026-05-07).