Mortgage Calculator
Estimate your mortgage payment in seconds. Enter the home price, down payment, interest rate, and loan term — this free mortgage calculator shows your monthly payment, compares biweekly payments (pay half every two weeks to cut years off your loan), and builds a full amortization schedule. Works for homebuyers in every state, including Idaho, Alabama, Montana, and Louisiana. Runs entirely in your browser.
Frequently Asked Questions
How is a mortgage payment calculated?
The principal-and-interest payment uses the standard amortization formula: payment = loan × [r(1+r)n / ((1+r)n − 1)], where r is the monthly interest rate (APR ÷ 12) and n is the number of monthly payments. Your real-world bill also includes property taxes, homeowners insurance, and possibly PMI — this calculator covers principal and interest so you can compare loans apples to apples.
What is a biweekly mortgage payment, and how much does it save?
With a biweekly plan you pay half your monthly payment every two weeks. Because there are 26 two-week periods in a year, you make the equivalent of 13 monthly payments instead of 12 — that one extra payment goes straight to principal. On a typical 30-year loan it shaves roughly 4–7 years off the term and saves tens of thousands in interest. The calculator above shows your exact savings.
Does this work as a mortgage calculator for Idaho, Alabama, Montana, or Louisiana?
Yes. Mortgage math is identical in every state — only your local inputs change: home prices, property-tax rates, and insurance costs differ between Idaho, Alabama, Montana, Louisiana, and everywhere else. Enter your numbers above and you get an accurate payment estimate for any state. For a complete monthly budget, add your local property tax and insurance to the result.
How much house can I afford?
A common rule of thumb: lenders typically approve a total housing payment (principal, interest, taxes, insurance) of up to about 28% of your gross monthly income, with all debts under about 36%. Try entering different home prices above until the monthly payment fits your budget.
Why does the amortization schedule show mostly interest at first?
Early in the loan your balance is largest, so interest takes the biggest share of each payment. As the balance shrinks, more of each payment goes to principal. On a 30-year loan, roughly the first decade is interest-heavy — which is exactly why extra principal payments (like biweekly's hidden extra payment) cut the term so dramatically.
Is this mortgage calculator's math accurate?
Yes — it uses the standard fixed-rate amortization formula used by lenders. It excludes taxes, insurance, PMI, and HOA fees, which vary by property and state. Your lender's Loan Estimate is the final word, but this calculator is accurate for principal and interest on a fixed-rate mortgage.