Mortgage Calculator
Calculate your monthly mortgage payment, total interest, and full amortization schedule for any home price, down payment, rate, and term. Private & in-browser — nothing leaves your device.
Show amortization schedule
| Year | Annual Payment | Principal | Interest | Balance |
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Annual totals. Small rounding differences (<$1) may appear; totals match.
Show month-by-month detail
| Month | Payment | Principal | Interest | Balance |
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How is the monthly mortgage payment calculated?
Mortgages use the reducing-balance (amortization) formula:
- P — Loan amount (Home Price − Down Payment)
- r — Monthly interest rate = Annual Rate ÷ 12 ÷ 100
- n — Number of monthly payments = Term in Years × 12
Worked example: $400,000 home, $80,000 down (20%), 7.0% annual rate, 30 years.
Loan P = $320,000 • r = 7.0 ÷ 12 ÷ 100 = 0.005833 • n = 360
(1 + 0.005833)360 ≈ 8.1165
Monthly Payment = 320,000 × 0.005833 × 8.1165 ÷ (8.1165 − 1) ≈ $2,129/mo
Total paid = $2,129 × 360 = $766,440 • Total interest = $766,440 − $320,000 = $446,440
Each payment is the same dollar amount every month, but the split between interest and principal changes: early payments are mostly interest; later payments are mostly principal. This is why extra payments made early in the loan save the most interest.
Monthly payment on a $300,000 loan — rate & term comparison
Values are principal & interest only. Click any cell to load those parameters into the calculator.
| Rate | 15 years | 20 years | 30 years |
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Property taxes, insurance, and PMI are not included. Actual payment will be higher.
Frequently asked questions
How is a monthly mortgage payment calculated?
A mortgage uses the reducing-balance formula: Monthly Payment = 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 ÷ 12 ÷ 100), and n is the number of monthly payments (term in years × 12). This gives a fixed payment that covers both interest and principal each month, with the interest portion shrinking and the principal portion growing over time.
What is the monthly payment on a $300,000 mortgage at 7% for 30 years?
For a $300,000 loan at 7% annual interest for 30 years (360 payments): monthly rate r = 7/12/100 = 0.005833. Monthly payment ≈ $1,996. Total paid over 30 years ≈ $718,560. Total interest ≈ $418,560. You can verify this with the calculator above or click any cell in the reference table.
Does a larger down payment lower my monthly payment?
Yes. A larger down payment reduces the loan principal, which directly lowers your monthly payment and the total interest you pay. Additionally, a down payment of 20% or more typically eliminates Private Mortgage Insurance (PMI), saving 0.5–1.5% of the loan amount per year. This calculator shows the down payment, principal, and interest proportions in the breakdown bar.
What is the difference between a 15-year and 30-year mortgage?
A 15-year mortgage has a higher monthly payment but dramatically lower total interest. For example, on a $300,000 loan at 7%: the 30-year term costs approximately $419K in interest; the 15-year term costs only about $186K in interest — saving $233K — but the monthly payment is about $580 higher. Use the reference table below to compare across rates and terms.
Does this calculator include property taxes and insurance (PITI)?
This calculator computes the principal and interest (P&I) portion of your mortgage payment — the part that goes to your lender. It does not include property taxes, homeowner's insurance, or PMI, which vary by location and loan. Your total monthly housing cost (PITI) will be higher than the figure shown here.
What is an amortization schedule?
An amortization schedule shows how each monthly payment is split between interest and principal over the life of the loan. In early payments, most of the money goes toward interest. Over time, as the principal balance decreases, more of each payment reduces the loan. The full year-by-year and month-by-month breakdown is available in the "Show amortization schedule" section below the calculator.