Mortgage Calculator
Estimate monthly payments, total interest, and repayment cost. e.g. “What would a $250,000 mortgage cost each month?”
Enter your values
Results update as you type. All calculation happens in your browser.
Methodology
Estimate monthly payments, total interest, and repayment cost. This tool uses a standard, documented formula and runs entirely on your device.
Last reviewed January 2026 · Runs client-side
Understanding your monthly mortgage payment
A mortgage payment is rarely just principal and interest. On most home loans the amount that leaves your account each month also covers property tax, homeowners insurance, and, in many communities, HOA fees. Two mortgages with the same interest rate can still have very different monthly costs once those extras are included, which is why this calculator separates principal and interest from the rest.
The interest portion is front-loaded. Early in a 30-year loan, most of each payment goes toward interest rather than reducing the balance, which is why the total interest over the life of a loan can rival or exceed the amount borrowed. Seeing the payoff date and total interest up front helps you judge whether a shorter term or extra payments are worth it.
How to use this calculator
- Enter the home price and your down payment, the difference is the amount you actually finance.
- Add the interest rate a lender has quoted you and the loan term in years.
- Fill in annual property tax, insurance, and any monthly HOA to see the full housing cost, then read the payoff date and total interest.
What the inputs mean
- Home price & down payment
- The loan principal is the price minus your down payment. A larger down payment lowers both the payment and the total interest.
- Interest rate
- The annual rate your lender quotes. It is entered manually, FinDock does not look up live rates.
- Property tax & insurance
- Entered annually and divided across twelve months. These vary widely by location and property.
On a $250,000 home with $50,000 down at 6.5% over 30 years, principal and interest come to about $1,264/month. Add $200 of tax, $75 of insurance, and the monthly housing cost is roughly $1,542, and you would pay over $200,000 in interest across the full term.
The formula, in plain terms
The principal-and-interest payment uses the standard amortization formula M = P·r(1+r)ⁿ / ((1+r)ⁿ−1), where P is the loan amount, r is the monthly rate (annual ÷ 12), and n is the number of monthly payments.
Good to know
- A rate that looks only slightly higher can add tens of thousands in interest over 30 years, compare the total interest, not just the rate.
- Property tax and insurance are estimates you enter; your lender's escrow figures may differ.
Frequently asked questions
Does this include PMI?
No. Private mortgage insurance depends on your lender and equity. If you expect PMI, add its monthly cost to the insurance field for a fuller estimate.
Why is my lender's payment slightly different?
Lenders may round differently, use a different day-count convention, and set escrow amounts based on their own tax and insurance figures. Treat this as a close estimate.
How much does a bigger down payment help?
It reduces the financed principal directly, which lowers both the monthly payment and the total interest. Try a few values to see the effect.
Last reviewed January 2026. This explainer is general information, not professional advice.