Mortgage Calculator

Calculate your monthly payment, total interest, and amortization schedule.

$
$
%
years
$
Monthly Payment (P&I)
$1,770.53
Principal & Interest on a $280,000 loan
Total Interest
$357,390.80
Total Cost
$637,390.80

How to Use This Mortgage Calculator

  1. Enter the home price — the total purchase price of the property you're considering.
  2. Set your down payment — use the slider or type an amount. A 20% down payment avoids PMI (Private Mortgage Insurance).
  3. Enter the interest rate — check current rates from your lender or use the default as a starting point.
  4. Choose your loan term — 30 years is most common, but 15-year loans have lower interest rates and less total interest.
  5. Add extra payments — see how additional monthly payments reduce your total interest and shorten the loan.

Understanding Your Mortgage Payment

Your monthly mortgage payment consists of principal (the amount that reduces your loan balance) and interest (the cost of borrowing). In the early years of your mortgage, most of your payment goes toward interest. Over time, the balance shifts toward principal — this is called amortization.

The Mortgage Payment Formula

This calculator uses the standard amortization formula:

M = P × [r(1+r)n] / [(1+r)n - 1]

Where M = monthly payment, P = principal (loan amount), r = monthly interest rate, and n = total number of payments.

30-Year vs 15-Year Mortgage

A 30-year mortgage has lower monthly payments but you pay significantly more in total interest. A 15-year mortgage has higher monthly payments but saves tens of thousands in interest. For example, on a $280,000 loan at 6.5%: a 30-year loan costs $357,391 in interest, while a 15-year loan costs only $158,840 — a savings of nearly $200,000.

The Impact of Extra Payments

Making extra payments toward your mortgage principal can dramatically reduce the total interest paid and shorten your loan term. Even $100/month extra on a $280,000 loan at 6.5% saves over $61,000 in interest and pays off the mortgage 5 years early. Use the extra payment field above to see the impact on your specific loan.

Frequently Asked Questions

The monthly payment is calculated using the amortization formula: M = P[r(1+r)^n] / [(1+r)^n - 1], where P is the principal loan amount, r is the monthly interest rate (annual rate divided by 12), and n is the total number of monthly payments (years times 12). This formula ensures each payment covers both principal repayment and interest.
A mortgage payment typically includes principal, interest, property taxes, and homeowners insurance (PITI). This calculator shows the principal and interest portion. Property taxes and insurance vary by location and should be added separately to estimate your total monthly housing cost.
A common guideline is the 28/36 rule: your monthly mortgage payment should not exceed 28% of your gross monthly income, and your total debt payments should not exceed 36%. For example, with a $6,000/month gross income, aim for a mortgage payment under $1,680/month.
Yes, making extra payments toward principal can significantly reduce the total interest paid and shorten your loan term. Even small additional monthly payments can save thousands of dollars over the life of the loan.
Private Mortgage Insurance (PMI) is required when your down payment is less than 20% of the home price. PMI typically costs 0.5% to 1% of the loan amount per year. Once you reach 20% equity in your home, you can request to have PMI removed.