Mortgage Calculator
Calculate your monthly mortgage payment, total interest, and full cost of a home loan.
Estimate your total monthly mortgage payment — principal, interest, property tax, homeowners insurance, and PMI — for any home price, down payment, term, and rate.
How Mortgage Calculator Works
The calculator splits your monthly payment into two parts. First it works out the standard principal & interest (P&I) payment using the amortization formula M = P × [r(1+r)^n] / [(1+r)^n − 1], where P is the loan amount (home price minus down payment), r is the annual interest rate divided by 12, and n is the number of monthly payments (loan term in years × 12).
It then adds your annual property tax and homeowners insurance, divided by 12, plus private mortgage insurance (PMI) if your down payment is below 20% of the home price — lenders typically require PMI in that case, charged as a percentage of the loan balance per year.
The pie chart breaks the total cost of the loan into principal, interest, tax, and insurance so you can see how much of your payment goes toward building equity versus interest and fees.
See It In Action
Who Uses Mortgage Calculator and Why
- Comparing how a 15-year versus 30-year term changes your monthly payment before you talk to a lender.
- Working out whether a 20% down payment is worth saving for, since it removes the PMI charge added on top of principal, interest, tax, and insurance.
- Estimating your full monthly housing cost, including property tax and homeowners insurance, before house-hunting in a specific price range.
- Testing how a rate change of even half a percent (say, from 6.5% to 7%) shifts your monthly principal & interest payment on the same loan amount.
Mistakes to Avoid
- Entering the home price as the loan amount — the calculator subtracts your down payment from the home price to get the loan amount, so double-subtracting it yourself understates the payment.
- Forgetting to add property tax and insurance and comparing the principal & interest figure alone against a lender's quoted "full payment," which almost always includes tax and insurance.
- Assuming PMI applies at any down payment below 20% at a flat rate you guessed — PMI is charged as a percentage of the loan balance, so entering an inaccurate PMI rate can meaningfully skew the total monthly payment.
Tips for Best Results
- If you're deciding between loan terms, run the same home price and rate at both 15 and 30 years side by side — the payment difference is often smaller than the total-interest difference.
- Put in your actual local property tax rate and homeowners insurance quote rather than a rough guess; those two line items can add hundreds of dollars a month on top of principal and interest.
Fixing Common Problems
My total monthly payment looks lower than what my lender quoted. — Check whether you included property tax, homeowners insurance, and PMI (if your down payment is under 20%) — lenders bundle all of these into the payment they quote, while this calculator only adds them if you enter them.
The PMI line isn't showing up even though my down payment is small. — PMI is only added automatically when the down payment is below 20% of the home price — confirm your down payment and home price fields are both filled in correctly, since PMI is calculated off the loan amount those two produce.
Terms Explained
PMI (Private Mortgage Insurance): An extra monthly charge lenders typically require when a down payment is below 20% of the home price, calculated as a percentage of the loan balance.
Principal & Interest (P&I): The core monthly loan payment covering the amortization formula alone, before property tax, insurance, or PMI are added.