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Mortgage Calculator

Standard fixed-rate mortgage math, transparent. Computes your monthly payment, total cost over the life of the loan, and how much of the very first payment lands on principal vs. interest.

Monthly Payment

$2,528.27

principal + interest

Loan amount
USD
Annual interest rate
%
Loan term
years
Total paid over life
$910,178
Total interest
$510,178
Loan principal
$400,000
Total months
360
Month 1 → principal
$361.61
Month 1 → interest
$2,166.67
How this is calculated

M = P × (r(1+r)^n) ÷ ((1+r)^n − 1)

where P = loan principal, r = monthly rate (annual rate ÷ 12 ÷ 100), n = total monthly payments (years × 12). For rate = 0, M = P ÷ n.

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FAQ

Common questions

Does this calculator include taxes, insurance, and PMI?

No, this is a clean principal-and-interest (P&I) calculation. Taxes, homeowner's insurance, HOA dues, and PMI are typically escrowed by your lender and added on top. For a true monthly out-the-door figure (PITI), add those line items separately.

Why does so much of my early payment go to interest?

Amortization works on the outstanding balance. Early on, the balance is huge, so the interest portion (balance × monthly rate) dominates. As principal pays down, the interest share shrinks and the principal share grows. By year 15 of a 30-year mortgage, the split is roughly 50/50.

Should I take the 30-year or 15-year term?

Mathematically, a 15-year term saves enormous interest because the loan compounds for half as long. Practically, the 30-year term has a lower required monthly payment and gives you flexibility, you can voluntarily prepay to mimic the 15-year schedule when you want. Most operators take the 30-year and prepay strategically.

How does a small rate change affect total cost?

A lot. On a $400K, 30-year loan, moving from 6.5% to 7.5% adds roughly $260/month and over $90,000 in lifetime interest. Always run the calculator across the rate range your lender is quoting before locking, and ask whether buying down the rate (points) pencils for your hold period.
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