See exactly how each payment splits between principal and interest over the life of your loan
An amortization schedule shows exactly how each monthly mortgage payment is split between principal and interest over the life of your loan. In the early years, most of your payment goes toward interest. Over time, the balance shifts — and extra payments can save you tens of thousands of dollars. Use this free calculator to see your full payment breakdown, total interest cost, and how extra payments accelerate your payoff date.
When you take out a 30-year fixed mortgage, your monthly payment stays the same — but the composition changes every month. On a $680,000 loan at 6.75%, your first payment allocates $3,825 to interest and only $585 to principal. By year 15, the split is roughly even. By your final payment, nearly the entire amount goes to principal. This front-loading of interest is why extra payments early in the loan have the biggest impact.
California homebuyers with a median purchase price of $850,000 and 20% down will pay approximately $477,000 in total interest over 30 years at 6.75%. Adding just $200/month in extra payments saves over $68,000 in interest and pays off the loan 4.5 years early. The calculator below models your exact scenario.
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An amortization schedule is a table showing every monthly mortgage payment broken down into principal (the amount reducing your loan balance) and interest (the lender's charge for borrowing). It tracks your remaining balance after each payment through the full loan term.
Extra payments go directly toward principal, reducing your balance faster. This means less interest accrues on future payments, shortening your loan term and saving significant money. On a $680,000 California mortgage, an extra $300/month saves approximately $85,000 in interest.
Interest is calculated on your outstanding balance each month. Early in the loan, your balance is highest, so the interest charge is largest. As you pay down principal, less interest accrues each month, and more of each payment goes toward principal. This is the amortization curve.
A 15-year mortgage has higher monthly payments but dramatically lower total interest. On a $680,000 loan at 6.5%, a 30-year term costs $477K in interest while a 15-year costs $192K — saving $285,000. The monthly payment is roughly $1,600 higher on the 15-year.
Yes, but refinancing resets the amortization clock. If you're 10 years into a 30-year mortgage and refinance into a new 30-year, you restart the interest-heavy early years. Consider refinancing into a shorter term to avoid this — or compare the total cost using the calculator above.
Last updated: July 2026. Sources: Federal Housing Finance Agency (FHFA) 2025 conforming loan limits. U.S. Department of Housing and Urban Development (HUD) FHA Mortgage Insurance guidelines. U.S. Department of Veterans Affairs VA Home Loan program. CalHFA down payment assistance program rules. California county property tax rates per county assessor offices. Calculations are estimates for educational purposes only.
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