Mortgage Calculator

Enter home price, down payment, interest rate, and loan term to see your monthly payment and total cost before you sign anything.

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Mortgage Calculator

Estimate your monthly mortgage payment based on home price, down payment, interest rate and loan term.

Monthly Payment $0.00
Total Interest $0.00
Total Cost $0.00

The Mortgage Payment Formula

Monthly mortgage payments are calculated using the standard amortization formula: M = P × [r(1+r)^n] ÷ [(1+r)^n − 1], where M is monthly payment, P is loan amount (home price minus down payment), r is monthly interest rate (annual rate ÷ 12), and n is total payments (years × 12).

For a $300,000 home with a $60,000 down payment (20%), 6.5% annual rate, and 30-year term: P = $240,000, r = 0.065/12 = 0.00542, n = 360. Monthly payment = $1,517.86. Total paid over 30 years = $546,428 — meaning you pay $306,428 in interest on a $240,000 loan.

How Down Payment Affects Your Monthly Cost

A larger down payment reduces both your loan amount and your monthly payment. It also eliminates Private Mortgage Insurance (PMI), which lenders require when your down payment is under 20% (typically 0.5–1% of the loan amount annually). On a $300,000 home, PMI can add $100–200/month to your payment — a cost not included in basic mortgage calculators.

15-Year vs 30-Year Mortgage

A 15-year mortgage has higher monthly payments but dramatically lower total interest. On the same $240,000 loan at 6.0%: 30-year = $1,439/month, $277,993 total interest. 15-year = $2,026/month, $124,631 total interest. The 15-year saves $153,362 in interest but costs $587 more per month. Run both scenarios to find which fits your cash flow. Read the mortgage calculator guide →

Frequently Asked Questions

How is a monthly mortgage payment calculated?

Using the amortization formula: M = P × [r(1+r)^n] ÷ [(1+r)^n - 1], where P is loan principal, r is monthly interest rate (annual ÷ 12), and n is number of monthly payments (years × 12).

Does this calculator include property taxes and insurance?

No — this calculator shows principal and interest only. Your actual monthly housing cost (PITI) also includes Property taxes, Insurance (homeowners), and potentially PMI (if down payment < 20%). Add $300-800/month for these costs depending on your location and home value.

What is PMI and when is it required?

Private Mortgage Insurance (PMI) is required when your down payment is less than 20% of the home price. It typically costs 0.5-1% of the loan amount annually, added to your monthly payment. PMI is removed once your equity reaches 20%.

Should I choose a 15-year or 30-year mortgage?

A 30-year mortgage has lower payments but far higher total interest. A 15-year mortgage costs more per month but saves tens of thousands in interest. Choose 30-year if cash flow is tight; choose 15-year if you can handle higher payments and want to build equity faster.

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