Best Mortgage Calculator Ever
bold name, honest math

The Loan

Enter price, down payment, rate & term — we compute the monthly payment.

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Monthly costs beyond P&I

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Extra payments

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Total monthly payment
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principal & interest + taxes, insurance…

Balance over time

Amortization schedule

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Verification — ground-truth reference loans

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These tests run in your browser on every load. Payments are checked against published figures for canonical loans; reverse-solve and the schedule are checked for internal consistency (every dollar of principal accounted for, balance lands exactly at zero).

Mortgage calculator FAQ

The math behind each tool, in plain English.

How is my monthly mortgage payment calculated?

Your principal-and-interest payment uses the standard amortization formula: M = P·i(1+i)ⁿ ⁄ ((1+i)ⁿ−1), where P is the loan amount, i is your monthly interest rate (annual rate ÷ 12) and n is the number of months. This calculator then adds property tax, homeowners insurance, PMI and HOA to show your full monthly cost (PITI).

How much do extra payments save?

Every dollar paid above your scheduled payment goes straight to principal, so you owe interest on a smaller balance for the rest of the loan. Even $100–$200 a month can cut years off a 30-year mortgage and save tens of thousands in interest. The extra-payment slider shows your exact new payoff date and total interest saved.

When does refinancing make sense?

Refinancing pays off once your monthly savings have covered the closing costs — the "break-even" month. If you'll keep the home past that point, it's usually worth it; if you might move or refinance again sooner, it may not be. The Refinance tool shows the exact month you come out ahead.

What is a mortgage recast?

A recast (re-amortization) applies a lump sum to your principal and recalculates a lower monthly payment over the same remaining term, keeping your original payoff date and interest rate. It's far cheaper than refinancing — most calculators skip it entirely. The Recast tool also compares recasting against simply prepaying.

Do biweekly payments pay off a mortgage faster?

Yes. Paying half your monthly payment every two weeks makes 26 half-payments a year — the equivalent of one extra full payment — which typically shaves 4–6 years off a 30-year loan and saves significant interest, with no change to your budget beyond the calendar.

Are mortgage points worth it?

Discount points lower your interest rate but cost cash upfront (one point equals 1% of the loan). They pay off if you keep the loan past the break-even month, when the reduced payment has repaid the cost. If you might sell or refinance sooner, skip them. The Points tool finds your exact break-even.

How much house can I afford?

Lenders use debt-to-income ratios — commonly 28% of gross monthly income for housing and 36% for total debt (the "28/36 rule"). Enter your income, monthly debts and down payment in the Affordability tool to see a realistic maximum price, including taxes, insurance and PMI.

Is it better to rent or buy?

It depends on how long you'll stay, how fast the home appreciates, and what your down payment could earn if invested instead. The Rent vs Buy tool factors in that opportunity cost — not just the mortgage — to show the year buying actually pulls ahead of renting.

About the math

Payment uses the standard amortizing formula  M = P·i(1+i)ⁿ ⁄ ((1+i)ⁿ−1), with i = annual rate ⁄ 12 and n = months (the zero-interest case falls back to P ⁄ n). Rate is solved by bisection; term and loan amount have closed forms. The schedule uses the rounded monthly payment and trues up the final payment so the balance reaches exactly zero — the way a real servicer amortizes. PMI is charged while loan-to-value exceeds 80% and drops automatically thereafter. Not financial advice.