Mortgage Payoff and Amortization Calculator
Watch how every payment splits between interest and principal — and what happens when you pay a little extra.
What This Calculator Does
The calculator builds a year-by-year schedule for your loan: interest paid, principal paid, and the balance remaining at the end of each year. Add an extra monthly amount or switch to a biweekly schedule and it recalculates the payoff date and total interest alongside the original plan.
Who Is This For
Homeowners who want to know exactly where their payments are going, owners planning to be mortgage-free before retirement, and anyone deciding whether spare cash is better spent on the loan or somewhere else.
How It Works
Enter your loan amount, interest rate, and term to generate the base schedule. Then add an extra monthly payment or select the biweekly option to compare payoff timelines and total interest against the original loan.
Frequently Asked Questions
Why is so much of my early payment interest?
Interest is charged on the outstanding balance, and the balance is at its highest on day one. Early payments are therefore interest-heavy and the split shifts toward principal only gradually. That is also why extra principal applied in the first years does far more work than the same amount applied near the end.
How does the biweekly strategy work?
You pay half your monthly amount every two weeks. Because there are 52 weeks in a year, that produces 26 half payments — the equivalent of 13 monthly payments instead of 12. The extra payment goes straight to principal, shortening the term without a large change to your budget.
Do extra payments really save that much?
They can, because every dollar of extra principal removes all the future interest that dollar would have accrued. The saving grows with the size of the extra payment and with how early you start. Confirm with your servicer that extra funds are applied to principal rather than held as a prepaid future installment.
Should I pay off my mortgage early?
It depends on what else the money could do. Paying down a mortgage delivers a guaranteed return equal to your interest rate, which is compelling when the rate is high and less so when it is low relative to other options. Weigh it against retirement contributions, an emergency reserve, and higher-rate debt before committing.
Is there a prepayment penalty?
Most standard conforming mortgages have none, but some portfolio and investor loans do, often only in the first few years. Check your note or ask your servicer directly before you start making large extra payments.