Mortgage Amortization Calculator
Calculate a mortgage payment and view the complete principal, interest and remaining-balance schedule.
Loan Details
Freddie Mac PMMS, November 5, 2026. Conventional market benchmark, not an APR or lender quote.
Auto-fills available estimates after five digits. You can edit both costs below.
Monthly Costs
$417/month
$117/month
Mortgage amortization schedule, formula and examples
Quick answer: An amortization schedule divides each fixed payment between interest and principal. Early payments are interest-heavy because interest is calculated on a larger balance; the principal share grows as the balance declines.
What the schedule shows
For fixed-rate loans, each row should identify payment, interest, principal and remaining balance so you can audit how the mortgage loan amortizes and the total interest paid.
Extra-payment effect
Additional principal reduces the balance used for later interest calculations. Confirm that your servicer applies extra funds to principal.
30-year versus 15-year
A shorter term usually raises the required payment but can reduce lifetime interest. Compare both payment and total cost.
Scenarios to calculate
- Generate a 30-year mortgage amortization table.
- Compare one extra payment per year with a fixed monthly extra amount.
- Model the remaining balance before a sale or refinance.
Next: estimate the complete mortgage payment, plan an early mortgage payoff, compare a refinance scenario.
How Does a Mortgage Amortization Schedule Work?
A mortgage amortization schedule shows how each payment splits between principal (balance reduction) and interest (lender profit). In Year 1 of a 30-year mortgage, over 80% of each payment is interest—not equity. The table above shows your exact principal-interest split for every month of your loan term.
Why Do You Pay Mostly Interest in the First Years?
Because interest is calculated based on your outstanding loan balance, your highest interest payments occur at the very beginning of the loan.
- Years 1-7: The massive majority of your monthly payment goes directly to interest. You are building equity at a painfully slow pace.
- Years 15-20: The "tipping point." The scales finally balance, and your payment starts going more toward principal than interest.
- Years 25-30: Your loan balance is incredibly low, meaning very little interest is generated. Almost your entire monthly payment goes directly to principal.
How Do Extra Mortgage Payments Speed Up Your Loan Payoff?
When you make an "Extra Principal" payment, you instantly jump forward in the amortization schedule. Every $100 you pay early directly reduces the outstanding balance, meaning the bank can never charge you compound interest on that $100 again.
By looking at our amortization chart, you can clearly see the impact of adding just $200 a month in extra payments. On a $400,000 mortgage at 7%, paying an extra $200 a month will shave roughly 6 years off the loan and save you tens of thousands of dollars in lifetime interest.
Frequently Asked Questions
Can an amortization schedule change?
Only under three circumstances: 1) You have an Adjustable-Rate Mortgage (ARM) where the rate resets, 2) You "recast" your loan by making a massive lump-sum payment and having the lender recalculate the payment, or 3) You refinance into an entirely new loan.
Are bi-weekly payments worth it?
Yes. By dividing your monthly payment in half and paying it every two weeks, you end up making 26 half-payments a year (which equals 13 full payments). That one "hidden" extra payment per year dramatically speeds up your amortization schedule. Try toggling the "Bi-Weekly" switch in our calculator to see the math.
Continue your financial research
Use these closely related USFinNexus guides and tools to plan your next step.
Illustrative comparison scenarios
| Term | Monthly P&I | Scheduled interest |
|---|---|---|
| 10 years | $3,406 | $108,773 |
| 15 years | $2,613 | $170,398 |
| 20 years | $2,237 | $236,813 |
| 25 years | $2,026 | $307,686 |
| 30 years | $1,896 | $382,633 |
Educational scenarios, not quotes, approvals, investment forecasts or tax advice. See methodology and limitations.