Mortgage Calculator

Estimate your monthly mortgage payment with a complete breakdown of principal, interest, taxes, insurance, PMI, and HOA.

By Drew Budwin · Last updated July 2026 · Methodology

Pay half your principal and interest every two weeks and you make 26 half-payments a year, the same as one extra full payment. You pay the loan off sooner and owe less interest.

Already have a mortgage? See how extra payments can save you thousands with the Mortgage Payoff Calculator.

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How We Calculate This

Monthly Principal & Interest (P&I)

Monthly principal and interest comes from the standard mortgage amortization formula:

M = P × [r(1+r)n] / [(1+r)n - 1]
  • M = Monthly payment (principal and interest only)
  • P = Loan amount (home price minus down payment)
  • r = Monthly interest rate (annual rate ÷ 12 ÷ 100)
  • n = Total number of payments (loan term in years × 12)

PMI (Private Mortgage Insurance)

PMI is calculated as an annual percentage of your original loan amount, divided by 12 to get the monthly cost. For example, a 0.5% PMI rate on a $280,000 loan = $280,000 × 0.005 ÷ 12 = $116.67/month. PMI is automatically removed once your remaining balance drops to 80% of the original home price (LTV ≤ 80%). If your down payment is 20% or more, PMI is never applied.

Property Tax & Insurance Estimates

Enter a home price and two fields fill in from national averages: property tax at 1.1% of home value per year, homeowners insurance at 0.35%. Both carry an "(estimated)" tag. They're starting points, not your actual rates, so check what your county and insurer charge. Edit either field and the tag disappears. Your number stays.

Amortization Schedule

Each month, interest is calculated on the remaining loan balance. The difference between your fixed monthly P&I payment and the interest charge goes toward reducing the principal. Early in the loan, most of your payment goes to interest; as the balance decreases, more goes to principal. The schedule shows year-by-year totals so you can see how your equity builds over time.

Mortgage Calculator Formula

The monthly principal and interest payment is calculated using the standard 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 monthly interest rate (annual rate divided by 12), and n is the total number of monthly payments (loan term in years times 12).

How to Use This Calculator

  1. Enter your Home Price, the total purchase price of the home.
  2. Enter your Down Payment in dollars or as a percentage using the toggle.
  3. Enter the Loan Term in years (e.g., 30 or 15).
  4. Enter the Annual Interest Rate for your mortgage.
  5. Optionally add property tax, insurance, PMI rate, and HOA fees for a complete picture.
  6. Click Calculate to see your monthly payment breakdown and amortization schedule.

Frequently Asked Questions

How is PMI calculated on a mortgage?

PMI (Private Mortgage Insurance) is calculated as an annual percentage of your original loan amount, typically ranging from 0.3% to 1.5%. For example, on a $270,000 loan with a 0.5% PMI rate, you would pay $1,350 per year or $112.50 per month. PMI is required when your down payment is less than 20% of the home price.

When does PMI go away?

PMI is automatically removed once your remaining loan balance drops to 80% of the original home price (i.e., when your loan-to-value ratio reaches 80% or lower). This happens naturally as you make payments and pay down principal. You can also reach this threshold faster by making extra payments toward principal using the Mortgage Payoff Calculator.

What's included in a monthly mortgage payment?

A monthly mortgage payment typically includes principal and interest (P&I), property taxes, homeowners insurance, PMI (if your down payment was less than 20%), and HOA fees if applicable. This is sometimes referred to as PITI (Principal, Interest, Taxes, Insurance). This calculator breaks down each component so you can see exactly where your money goes.

How much is property tax on a house?

Property tax rates vary significantly by location but average roughly 1.1% of a home's value per year in the United States. On a $350,000 home, that would be approximately $3,850 per year or $321 per month. This calculator pre-fills an estimate based on national averages, but you should check your local tax rate for a more accurate figure.

How much house can I afford?

While this calculator shows you what a specific mortgage will cost each month, the reverse question (how much house you can afford based on your income and expenses) requires a different approach. A common guideline is that your total monthly housing costs should not exceed 28% of your gross monthly income.

What is a good interest rate for a mortgage?

Mortgage interest rates fluctuate based on economic conditions, your credit score, loan type, and down payment size. A higher credit score (740+) and a larger down payment (20% or more) typically qualify you for lower rates. Use this calculator to compare how different interest rates affect your monthly payment and total cost over the life of the loan.

How does loan term affect monthly payments?

A shorter loan term (e.g., 15 years vs. 30 years) means higher monthly payments but significantly less total interest paid over the life of the loan. For example, a $280,000 loan at 6.5% costs about $1,770/month over 30 years versus about $2,441/month over 15 years. But the 15-year term saves nearly $198,000 in interest. Use the Loan Payment Calculator to compare different scenarios.

What is the difference between fixed-rate and adjustable-rate mortgages?

A fixed-rate mortgage locks in the same interest rate for the entire loan term, so your principal and interest payment never changes. An adjustable-rate mortgage (ARM) starts with a lower introductory rate for a set period (commonly 5 or 7 years), then adjusts periodically based on market indexes. This calculator models fixed-rate mortgages.

How do bi-weekly mortgage payments save money?

Instead of 12 monthly payments a year, you pay half your principal and interest every two weeks. That works out to 26 half-payments, the equivalent of 13 full monthly payments, so one extra payment goes straight to principal each year. On a $280,000 loan at 6.5%, that can shave several years off a 30-year term and save tens of thousands in interest. Turn on 'Compare bi-weekly payments' above to see your numbers. Only principal and interest accelerate; escrow items like taxes and insurance are collected separately.

Further Reading

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