Mortgage Amortization Calculator

What a mortgage amortization schedule actually shows

An amortization schedule turns a fixed-rate mortgage into a timeline of individual payments. Each row shows how much of that payment goes to interest, how much reduces principal, and what balance remains after the payment posts. That matters because a fixed monthly payment can feel flat even though the composition of the payment changes every month.

In the early years, interest usually consumes most of the payment because interest is calculated on the larger starting balance. As the balance shrinks, the interest charge for each month also shrinks, which lets more of the same payment reach principal. The schedule is the clearest way to see that transition rather than relying on a single total-interest number.

This is why an amortization calculator belongs next to, but not inside, a broader mortgage-payment tool. A mortgage calculator helps you size the payment. An amortization schedule helps you understand the path the debt follows after that payment is set.

How this mortgage amortization calculator builds the schedule

The worksheet starts with the standard amortization formula for a fixed-rate mortgage. That formula converts the loan amount, rate, and term into one constant monthly principal-and-interest payment. Once that payment is known, the page steps through the loan month by month. Each month it calculates interest on the current balance, subtracts that interest from the payment to get principal, and updates the remaining balance.

The same monthly rows are then rolled up into annual summary checkpoints. Those year-end totals make the long mortgage path easier to scan because they show how much principal and interest were paid in each year and what balance remained at the end of that year. The annual view is useful when you want a high-level checkpoint without reading all 180 or 360 monthly lines first.

The worksheet also highlights the first-year split between interest and principal, because that is often the moment borrowers realize how front-loaded mortgage interest can be. Understanding that early payment mix is important before you think about refinancing, accelerating the loan, or comparing one mortgage structure with another.

Worked example: 300,000 mortgage at 6.5% over 30 years

Suppose the mortgage balance is 300,000, the interest rate is 6.5%, and the term is 30 years. The scheduled monthly principal-and-interest payment is about 1,896.20. That does not mean 1,896.20 reaches principal. In the first month, about 1,625.00 goes to interest and only about 271.20 reduces the balance.

Over the first year, the total principal reduction is still modest relative to the payment stream because the balance remains large. That is the pattern many borrowers miss when they only look at the monthly payment headline. The schedule makes it obvious that the mortgage is amortizing, but it is not amortizing evenly between interest and principal.

As the years pass, the balance falls and the mix changes. The annual summary rows make that visible without forcing you to inspect every monthly line one by one. That is why this page combines the full table with annual checkpoints instead of leaving the user with one giant grid and no summary layer.

What this amortization estimate does not include

This page models principal and interest only. It does not include property taxes, homeowners insurance, mortgage insurance, HOA dues, late fees, escrow shortages, interest-rate resets, or extra principal. If you need the all-in monthly housing payment, use a broader mortgage or PITI calculator first and then return here for the debt schedule itself.

It is also not a substitute for the lender's legal disclosures. The real Loan Estimate, note, and servicing statements govern the payment amount, the rate, and the official payoff figures. Use this worksheet to understand the mechanics and timeline, then reconcile the result with the lender's documents before you rely on it for a real borrowing decision.