Mortgage Calculator

How to use this mortgage calculator

Enter your home price, down payment, annual interest rate, and loan term. The calculator instantly shows your monthly mortgage payment, total interest paid over the life of the loan, and a full amortization schedule breaking down how each payment splits between principal and interest.

Adjust any input and the results update in real time. The amortization table shows every monthly payment for the full term, so you can see exactly when your principal starts overtaking interest — a useful reality check for anyone considering early payoff.

The mortgage payment formula

Your monthly payment is calculated using the standard amortization formula:

M = P × [r(1+r)ⁿ] / [(1+r)ⁿ − 1]

Where M is the monthly payment, P is the loan principal (home price minus down payment), r is the monthly interest rate (annual rate divided by 12), and n is the total number of monthly payments (term in years times 12).

Worked example

Say you buy a $400,000 home with 20% down ($80,000) on a 30-year fixed mortgage at 6.5%. The loan principal is $320,000, the monthly rate is 0.065 ÷ 12 ≈ 0.005417, and the number of payments is 360. Plugging these in:

M = 320,000 × [0.005417(1.005417)³⁶⁰] / [(1.005417)³⁶⁰ − 1] ≈ $2,022.62

Over 30 years you'll pay back $728,142 — meaning interest ($408,142) is actually larger than the principal you borrowed. This is why even small rate differences matter so much. See our methodology page for the full derivation of every formula on this site.

What costs are included?

This calculator covers your principal and interest (P&I) — the core of your monthly mortgage payment. Your real monthly payment to the lender is usually higher because it also includes escrow items:

Lenders call the all-in figure PITI (Principal, Interest, Taxes, Insurance). When budgeting, plan for PITI rather than the P&I number this tool shows.

Typical monthly payments by loan size

At a 6.5% 30-year fixed rate (20% down), here's how principal & interest scale with home price. Use this to sanity-check the numbers you're considering.

15-year vs 30-year mortgage

Shorter terms mean higher monthly payments but dramatically less interest. On a $400,000 loan at typical 2026 rates:

The 15-year costs ~$800 more per month but saves over $310,000 in interest. For most borrowers, the right choice depends on whether you can comfortably afford the higher payment and whether you'd otherwise invest the difference. Read our full comparison: 15-Year vs 30-Year Mortgage: Which Is Better?

How lenders set your rate

The interest rate you're offered isn't arbitrary. Lenders adjust it based on:

• Credit score — 760+ usually unlocks the best tier; below 700 you'll pay noticeably more.
• Down payment size — larger down payments mean lower risk and lower rates.
• Loan term — shorter terms typically have lower rates.
• Loan type — conventional, FHA, VA, and jumbo loans price differently.
• Debt-to-income (DTI) ratio — most lenders want total debt payments under 43% of gross income.
• Macro rates — the Federal Reserve's policy rate and bond market conditions move everyone's rates together.

Tips to lower your payment

• Increase your down payment — every extra dollar reduces the principal you borrow.
• Shop around for rates — even a 0.5% difference on a $300k loan saves over $100/month.
• Choose a longer term — a 30-year mortgage has lower payments than a 15-year, but you'll pay more interest overall.
• Improve your credit score — borrowers with scores above 760 typically qualify for the best rates.
• Buy down the rate with points — upfront payment to the lender can lower your rate permanently; worth it if you'll stay 5+ years.
• Recast later — a lump-sum principal payment can reduce your monthly bill without refinancing.

When to refinance

Refinancing replaces your current mortgage with a new one. The rule of thumb is the "1% rule" — it usually makes sense if you can lower your rate by at least 1 percentage point. But the real test is the break-even calculation:

Break-even months = closing costs ÷ monthly savings

If refinancing costs $4,000 in closing and saves you $200/month, you break even at 20 months. Plan to stay in the home longer than that, and refinancing pays off. Our home affordability guide walks through how to weigh refinancing against other options.