How Is a Mortgage Payment Calculated?
Your monthly mortgage payment uses the standard amortization formula: M = P[r(1+r)^n] / [(1+r)^n - 1]. P is your loan amount, r is the monthly interest rate, and n is the total number of payments. Early payments go mostly to interest; later payments shift toward principal.
A complete PITI payment includes Principal, Interest, property Taxes, and Insurance. This calculator lets you add annual property tax and insurance to see your true monthly cost.
2025 US Mortgage Rate Outlook
30-year fixed mortgage rates in 2025 are generally in the 6.0–7.0% range depending on credit score, down payment, and lender. A 15-year mortgage typically carries a rate 0.5–0.75% lower, but with significantly higher monthly payments.
Frequently Asked Questions
How is my monthly mortgage payment calculated? +
Your monthly payment uses the amortization formula based on loan amount, annual interest rate, and term. This calculator also adds property tax and insurance to show your true total monthly cost (PITI).
Should I choose a 15-year or 30-year mortgage? +
A 15-year mortgage has higher monthly payments but you pay significantly less total interest and build equity faster. A 30-year has lower payments and more cash flow flexibility. Use this calculator to compare both scenarios.
What is PMI and when do I need it? +
Private Mortgage Insurance (PMI) is required when your down payment is less than 20%. It typically costs 0.5–1.5% of the loan amount annually. Once you reach 20% equity you can request removal.
How much house can I afford? +
A common guideline is the 28/36 rule: your mortgage payment should not exceed 28% of gross monthly income, and total debt payments should not exceed 36%. Use our salary calculator to see your gross monthly income.