Mortgage Amortization Basics

A fixed-rate mortgage payment stays constant while the interest portion declines and the principal portion rises over the loan term.

The amortization schedule lists each period's payment, interest, principal, and remaining balance.

Additional principal payments reduce total interest and may shorten the term. Calculators that support extra payments model this effect explicitly.

Verify prepayment terms with your lender — some loans include penalties or processing rules not captured in generic calculators.

• Fixed payments do not mean fixed principal/interest splits.
• Amortization schedules clarify total interest cost over time.
• Extra principal payments change total cost and duration.

Why is early interest higher?

Interest is calculated on the remaining balance. When the balance is largest at the start of the loan, the interest portion of each payment is also largest.