Mortgage & Loan Calculator
Calculate your monthly mortgage or loan payment, total interest, and payoff timeline — with optional taxes, insurance, PMI, HOA, and extra payments.
How to use the mortgage calculator
- 1
Enter the home or loan price and your down payment.
- 2
Enter your interest rate and pick a loan term (10, 15, 20, 30 years, or a custom term).
- 3
Optionally add property tax, insurance, PMI, and HOA dues for a full monthly payment estimate, plus an extra monthly payment to see how much time and interest it saves.
- 4
Your monthly payment, total interest, and payoff timeline update instantly as you type.
How to calculate your mortgage payment
Every fixed-rate mortgage or loan payment uses the same amortization formula:
M = P × [r(1+r)^n] ÷ [(1+r)^n − 1]
Where M is your monthly principal & interest payment, P is the loan amount (home price minus down payment), r is your monthly interest rate (annual rate ÷ 12), and n is the total number of monthly payments (loan term in years × 12).
Worked example: a $280,000 loan (a $350,000 home with a $70,000 / 20% down payment) at 6.5% over 30 years: monthly rate r = 0.065 ÷ 12 = 0.005417, and n = 360 payments. Plugging into the formula gives a payment of $1,769.79 per month, totaling about $637,125 paid over 30 years — of which roughly $357,125 is interest.
Why amortization isn't linear: in the example above, the very first payment is $1,516.67 interest and only $253.12 principal — because interest is charged on the full $280,000 balance. By the final year of the loan, that ratio flips almost completely, with nearly the whole payment going to principal since the remaining balance is small. This is why paying down a mortgage early has an outsized effect on total interest in the early years of the loan.
What is PITI? The full cost of homeownership
PITI — Principal, Interest, Taxes, and Insurance — is what most lenders mean by your "full monthly payment," and it's usually higher than the principal-and-interest number alone.
- Principal & interest: repays the loan itself, fixed for the life of a fixed-rate loan.
- Property tax: set by your local government, typically collected monthly and held in escrow.
- Homeowners insurance: required by most lenders, also usually escrowed and paid annually on your behalf.
- PMI (private mortgage insurance): required on most conventional loans with less than 20% down, and typically removable once you reach 20% equity.
- HOA dues: not part of your loan at all, but a separate recurring cost in many communities that still affects what you can actually afford each month.
Worked example: on the $280,000 loan above with a $1,769.79 principal & interest payment, adding $3,600/year property tax ($300/mo), $1,200/year insurance ($100/mo), and $140/mo PMI brings the full PITI payment to $2,309.79 per month — about 30% higher than the principal-and-interest figure alone, which is why comparing loan offers on P&I only can be misleading.
How extra payments shorten your loan
Any extra amount you pay beyond your required monthly payment goes 100% toward reducing your principal balance — and since interest is recalculated on that lower balance every month going forward, extra payments compound in your favor for the rest of the loan.
Worked example: on the same $280,000 loan at 6.5% over 30 years, adding just $200/month extra toward principal pays off the loan in about 22 years 9 months instead of 30 years — saving 7 years 3 months and roughly $101,300 in interest, for a total extra outlay of only around $54,600 over that shorter period.
The earlier in the loan you start paying extra, the more you save, since more of each early payment would otherwise have gone to interest on a larger balance. Even a modest, sustainable extra payment — rather than a large one you can't maintain — tends to outperform sporadic lump-sum payments over time.
15-year vs. 30-year loan terms
| Loan term (on $280,000 at 6.5%) | Monthly P&I | Total interest paid |
|---|---|---|
| 15 years | $2,439.10 | $159,038 |
| 20 years | $2,087.60 | $221,025 |
| 30 years | $1,769.79 | $357,125 |
A 15-year loan costs about $670 more per month on this example, but pays off in half the time and saves roughly $198,000 in total interest compared to the 30-year term — a direct result of both the shorter timeline and the typically lower interest rate lenders offer on shorter terms.
The right choice depends on your monthly budget flexibility as much as the total savings: a 30-year term keeps payments lower and more resilient to income changes, while a 15-year term forces faster, cheaper equity building for those who can afford the higher payment. Use the loan term buttons in the calculator above to compare any two terms side by side on your own numbers.
Need to work out a discount, raise, or percentage change instead? Try the Percentage Calculator →
Frequently asked questions
Related guides
The exact amortization formula behind every mortgage payment, a full worked example, and how PITI (principal, interest, taxes, insurance) changes what you actually owe each month.
Read the guide →A side-by-side comparison of 15-year and 30-year mortgage terms on the same loan amount — monthly payment, total interest, and which one actually fits your budget.
Read the guide →How adding even a small extra amount to your monthly mortgage payment cuts years off your loan and saves tens of thousands in interest, with a full worked example.
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