Interest-Only Mortgage Calculator

Compare the initial interest-only payment with the higher payment required to amortize the unchanged principal over the remaining term.

Loan amount

Fixed rate (%)

Interest-only period (years)

Total loan term (years)

—Interest-only payment

—Later amortizing P&I

—Payment increase

—Modeled total interest

Principal remains unchanged during the interest-only periodThis simplified fixed-rate model does not include taxes, insurance, fees, rate resets, negative amortization, balloon terms, or lender-specific structures.

How to use the Interest-Only Mortgage Calculator

Enter the loan amount, rate, interest-only years, and total term. The tool shows the initial interest-only payment and then the payment needed to amortize the unchanged principal over the remaining term.

Important assumptions

The model holds the entered rate constant and assumes no principal reduction during the interest-only period. Real products can have adjustable rates, fees, balloon terms, different reset mechanics, taxes, insurance, or other features.