If you're planning to buy a home, understanding how your monthly mortgage payment is calculated is crucial. It's not just the price of the house divided by the number of months. It involves a specific mathematical formula that accounts for principal, interest, taxes, and insurance (PITI).
The Mortgage Payment Formula
Lenders use a standard amortization formula to calculate your monthly principal and interest payment:
M = P × [r(1+r)ⁿ] / [(1+r)ⁿ − 1]
- M = Total monthly payment
- P = The principal loan amount (home price minus down payment)
- r = Monthly interest rate (annual rate divided by 12)
- n = Number of payments (loan term in years multiplied by 12)
Factoring in Taxes and Insurance
Your total monthly payment isn't just principal and interest. Most lenders require you to pay 1/12th of your annual property taxes and homeowners insurance with your mortgage payment each month. This money goes into an escrow account.
Try It Yourself
Don't want to do the math by hand? We've built a free, easy-to-use tool that calculates all of this for you instantly. Just enter your home price, down payment, and interest rate.
Conclusion
Understanding this formula helps you see how even a small change in your interest rate or down payment can drastically affect your monthly costs. Use our tool to run different scenarios before you talk to a lender!