See the amortization schedule, not just the payment headline.
Track how each mortgage payment splits between principal and interest, and see what extra payments do to the payoff timeline.
See where every payment actually goes
Monthly payment calculators are useful, but amortization is where the shape of the loan becomes real. This page shows how much each month goes to interest, how slowly the balance moves at first, and what extra payments actually buy you.
Even small recurring extra payments usually matter more than people expect because they attack principal early, which reduces future interest compounding.
This page uses the standard amortized-loan payment formula and then simulates the balance month by month so you can see the interest and principal split directly.
If the payment would fail to reduce principal, the tool now stops and explains the problem instead of showing a misleading schedule.
A front-loaded interest curve is normal on a long fixed-rate loan. Extra payments matter most when they reach principal early enough to cut future interest.
This is a mathematical schedule estimate. It does not account for escrow changes, servicing fees, changing rates, or lender-specific payment application rules.
Maintained by David K. ยท Last reviewed: July 23, 2026