Answer: Enter the home price, down payment, rate, and term and the Mortgage Calculator returns your exact monthly payment with a full amortization breakdown of principal versus interest.
A mortgage calculator estimates your monthly home-loan payment by combining the loan amount, interest rate, and term, and shows how much of each payment goes to principal versus interest.
Estimate your monthly mortgage payment with taxes & insurance
Your monthly mortgage payment typically includes four components, known as PITI: Principal, Interest, Taxes, and Insurance. Principal is the part that actually pays down your loan. Interest is the lender's charge for the balance you still owe. Taxes and insurance don't go to the lender at all; they're collected into an escrow account each month and paid out to your county and insurer when the bills come due.
The split shifts dramatically over time. Early on, most of your check services interest, because the balance is at its largest. On a $320,000 loan at 6.5%, the very first payment is $1,733 of interest and just $289 of principal. Each month the balance drops a little, the interest charge shrinks, and more of the same payment goes to principal. That slow flip is called amortization, and the schedule below the results shows it year by year.
M = P × [r(1+r)^n] / [(1+r)^n - 1]
Where: M = Monthly payment, P = Principal (loan amount), r = Monthly interest rate (annual rate ÷ 12), n = Total number of payments. For a 30-year loan, n is 360; for a 15-year loan, 180. The formula only covers principal and interest; taxes and insurance are added on top, which is why this calculator asks for all four inputs.
Take the calculator's defaults: a $400,000 home with $80,000 down (20%, so no PMI), a 6.5% rate, and a 30-year term. The loan is $320,000. Run it through the formula and principal-plus-interest comes out to $2,023 a month. Property tax at 1.1% of the home's value adds $367 a month, and a $1,400-a-year insurance policy adds $117. Total PITI: about $2,506 a month.
The sobering number is the long-run total. Over 360 payments you'd hand the lender roughly $728,000, of which $408,000 is interest, more than the original loan. That's not a scam, it's just what 30 years of borrowing costs, and it's exactly why rate shopping and extra principal payments move the needle so much.
Principal and interest on a $320,000 loan over 30 years:
| Rate | Monthly P&I | Total interest over 30 years |
|---|---|---|
| 5.0% | $1,718 | $298,419 |
| 5.5% | $1,817 | $334,093 |
| 6.0% | $1,919 | $370,682 |
| 6.5% | $2,023 | $408,142 |
| 7.0% | $2,129 | $446,428 |
| 7.5% | $2,237 | $485,495 |
Each half-point costs about $100 a month on this loan size and $35,000 to $40,000 over the full term. If rates drop after you buy, that gap is what a refinance captures; our refinance break-even calculator tells you how long the closing costs take to pay back.
The same $320,000 at 6.5% over 15 years runs $2,788 a month, which is $765 more than the 30-year payment. In exchange, total interest falls from $408,000 to about $182,000, a saving of more than $226,000, and you own the house outright in half the time. The 30-year term isn't wrong, it buys flexibility and a lower required payment. But if the 15-year payment fits comfortably under 28% of your gross income, it's one of the cheapest forms of forced savings there is. A middle path: take the 30-year for safety and pay extra principal when you can.
For the full walkthrough of the math, see our guide on how to calculate a mortgage payment, and if you're still setting a budget, start with how much house you can afford.
A $400,000 home with 20% down ($80,000) leaves a $320,000 loan. At 6.5% over 30 years, the monthly principal-and-interest payment is 320,000 × [0.005417 × 1.005417360] ÷ [1.005417360 − 1] ≈ $2,023. Adding $200/month of extra principal cuts roughly 7 years off the term and saves over $100,000 of interest — model it with the extra-payments field above.
Use it to compare loan scenarios before you talk to lenders: different rates, terms, down payments, and extra-payment plans. It computes principal and interest only — your real monthly payment also includes property tax, homeowners insurance, and (below 20% down) PMI, which lenders bundle into an APR-based estimate.
1) Entering the home price instead of the loan amount — the calculator subtracts the down payment for you, so enter the price. 2) Comparing loans on rate alone: a 6.5% 30-year and a 6.0% 15-year produce wildly different total costs — always compare total interest, not just the monthly figure. 3) Forgetting closing costs (2–5% of the loan) when budgeting the cash you need at signing. 4) Assuming the payment stays flat in an ARM — this calculator models fixed rates.
The classic guideline is the 28/36 rule: keep the full housing payment under 28% of gross monthly income, and all debt payments combined under 36%. On a $100,000 income that caps housing around $2,333 a month, which supports roughly a $370,000 loan at 6.5% once taxes and insurance are counted. Lenders verify this through your debt-to-income ratio.
Four things, abbreviated PITI: principal, interest, property taxes, and homeowners insurance. Taxes and insurance are usually collected monthly into an escrow account and paid by the servicer. Put less than 20% down on a conventional loan and a fifth item, private mortgage insurance, joins the bill. HOA dues, where they apply, are paid separately.
More than it looks. On a $320,000 30-year loan, moving from 6.0% to 6.5% raises the payment from $1,919 to $2,023, about $104 a month, and adds roughly $37,500 in interest over the life of the loan. That's why shopping multiple lenders and paying down credit issues before applying has such a high payoff.
On a conventional loan, yes: 20% down means no private mortgage insurance. Below that, PMI typically runs about 0.3% to 1.5% of the loan per year until you reach 20% equity, when you can request cancellation. Many buyers still choose a smaller down payment and accept PMI to buy sooner; our PMI calculator prices both scenarios.