A mortgage amortization calculator shows how each fixed monthly payment is divided between interest and principal. This tool is for U.S. borrowers who want a month-by-month balance schedule instead of a single payment estimate.
Mortgage amortization calculator
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How to use this mortgage amortization calculator
- Enter the original amount borrowed, excluding any down payment.
- Provide the annual interest rate for the fixed-rate loan you want to model.
- Enter the repayment term in years.
- Review the totals, then scroll through the table to inspect any monthly payment.
How an amortization schedule is calculated
The mortgage amortization schedule calculator first determines the level monthly principal-and-interest payment. It converts the annual percentage rate to a monthly decimal rate, uses the term to find the number of payments, and applies the fixed-payment formula:
M = P × r × (1 + r)n ÷ ((1 + r)n − 1)
For every row, monthly interest equals the opening balance multiplied by r. Principal equals the payment minus that interest. The new balance is the prior balance minus principal. The mortgage calculator with amortization repeats those steps until the modeled balance reaches zero, adjusting the final payment for any small rounding remainder.
Worked amortization example
Assume an example $300,000 mortgage, a 6.5% annual rate, and a 30-year term. The calculated monthly principal-and-interest payment is approximately $1,896.20. During month one, interest is $300,000 × 0.065 ÷ 12, or $1,625.00. The principal portion is about $271.20, leaving an estimated balance of $299,728.80. Later payments direct progressively more money to principal because interest is calculated against a declining balance.
Run the mortgage amortization calculator with another lender-provided scenario to compare how a different rate or term changes the early payment split and lifetime interest. Use one consistent set of loan assumptions for each comparison.
Use this mortgage amortization calculator to locate the point when cumulative principal overtakes cumulative interest. That crossover depends on the rate, term, balance, and payment history, so treat the month as a model rather than a statement.
Assumptions and limits
- The schedule models a fully amortizing fixed-rate mortgage with payments made monthly.
- The interest rate is an example input; verify the applicable rate and terms with your lender.
- Property tax, homeowners insurance, HOA dues, PMI, closing costs, and servicing fees are excluded.
- The table assumes payments arrive as scheduled and includes no late charges or prepayments.
- Displayed cents may create a minor final-payment difference from a lender’s servicing system.
Mortgage amortization calculator FAQ
Why is interest largest near the beginning?
Interest is calculated from the unpaid balance. Because that balance is highest at origination, the interest share starts high and generally declines as principal is repaid.
Does amortization mean my payment changes every month?
Not for the fixed-rate structure modeled here. The scheduled principal-and-interest payment stays level, while the internal allocation gradually shifts from interest toward principal.
Can this table replace my lender’s statement?
No. Actual posting dates, rounding practices, escrow items, fees, and payment history can make a servicer’s figures different. Use your mortgage statement for the authoritative balance.
Related planning resources
Start with the approved mortgage payment calculator when you need a concise monthly estimate rather than all 360 rows. The high-yield savings account guide can help frame liquidity considerations before committing cash to principal. For broader loan education, review the Fannie Mae mortgage calculator guidance.
Last reviewed: October 5, 2026
Author: Harsh Kardam
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Disclaimer: This is an educational estimate, not a rate quote, approval, or financial, legal, or tax advice. Verify current rates, fees, and terms directly with your lender or provider.
