Free Mortgage Calculator
Estimate your monthly mortgage payments, see your exact principal and interest split, and test how extra payments cut years off your loan.
Enter your home price, down payment, and interest rate above to calculate your monthly mortgage payment instantly.
How to Use This Calculator
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1
Enter Home Price & Down Payment
Start with the home's purchase price and the cash you plan to put down. Tap the $ or % switch to flip between dollars and percentages. The helper line shows the real-time conversion between both units.
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2
Set Your Interest Rate & Loan Term
Type in your fixed annual interest rate (like 6.0%) and pick your loan timeline from the dropdown. 30 years is standard, but you can also compare 15 or 20-year terms.
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3
Add Optional Extra Monthly Payments
See what happens when you chip in extra toward your principal each month. If you leave this empty, the calculator runs a normal amortization schedule.
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4
Review Your Live Results
Everything updates as you type. Check your monthly principal and interest, your total lifetime financing cost, the visual breakdown bar, and how much time extra payments shave off.
The Formula
Fixed-rate mortgages are amortized using the standard financial payment formula:
Here is what each variable represents in plain English:
- M Monthly Mortgage Payment: The fixed sum you pay every month to cover principal and interest.
- P Principal Loan Balance: The actual cash you borrow from the bank (home price minus down payment).
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r
Monthly Interest Rate: Your annual interest rate divided by 12 months and divided by 100 (for example, a 6.0% annual rate becomes 0.06 ÷ 12 = 0.005 per month). At 0% interest, the equation simplifies to
M = P ÷ n. - n Total Monthly Payments: The lifetime payment count, found by multiplying loan years by 12 (a 30-year loan equals 30 × 12 = 360 payments).
Why extra monthly payments save so much cash: Extra dollars go straight to the principal, bypassing interest entirely. Because mortgage interest is recalculated each month against your remaining balance, shrinking that balance early starves future interest charges. Over a multi-decade loan, this compounds rapidly, cutting years off your mortgage and saving tens of thousands of dollars in interest charges.
Example
Let's walk through a typical home purchase using realistic numbers. We ran these exact figures through our own calculations. I haven't bought a home yet — I built this calculator partly to see what saving for one would actually take, and 20% keeps coming up as the target worth modeling. Here is how the math breaks down:
Applying the amortization formula step by step:
- Calculate compounding factor:
(1 + 0.005)³&sup6;° ≈ 6.022575 - Calculate numerator:
$300,000 × [0.005 × 6.022575] = $9,033.86 - Calculate denominator:
6.022575 − 1 = 5.022575 - Calculate monthly payment:
M = $9,033.86 ÷ 5.022575 = $1,798.65 per month - Total of 360 payments:
360 × $1,798.65 = $647,515 - Total lifetime interest paid:
$647,515 − $300,000 = $347,515 - Total overall cost of the property:
$75,000 (down payment) + $647,515 (payments) = $722,515
Because the buyer placed 20% down, Private Mortgage Insurance (PMI) is waived entirely, keeping monthly holding costs lower.
Frequently Asked Questions
What does a monthly mortgage payment include?
Most homeowners pay four pieces bundled together as PITI: Principal, Interest, Taxes, and Insurance. This calculator models your core principal and interest obligations. Local property taxes, homeowners insurance premiums, and any HOA dues vary by neighborhood, and lenders usually collect them separately through an escrow account.
How much down payment do I need?
Putting 20% down remains the classic target because it eliminates Private Mortgage Insurance (PMI) on conventional loans. Still, plenty of buyers start with 3% to 5% on conventional mortgages or 3.5% with FHA loans. Putting down less upfront helps you buy sooner, though your monthly payment and interest charges will run noticeably higher.
Should I choose a 15-year or 30-year mortgage?
A 15-year mortgage requires significantly higher monthly payments because you're compressing the debt into half the time, but it offers lower interest rates and saves a bundle over the life of the loan. No mortgage of my own yet, so I'll just say what the numbers here keep showing me: $53,000 in interest saved is a return most portfolios would envy. A 30-year loan keeps your mandatory payment lower, and you can always send extra principal whenever you feel like it.
Does paying $100 extra a month really help?
Yes, regular prepayments toward your principal balance deliver remarkable savings over the life of a loan. On our reference $300,000 30-year mortgage at 6% interest, adding just $100 extra each month pays off the loan 47 months (nearly 4 years) earlier and eliminates roughly $53,000 in interest expenses. Because prepayments compound over decades, starting early yields the maximum benefit.
How much does the interest rate change my payment?
Even small shifts in interest rates produce substantial differences in your monthly obligation and total financing cost. For example, on a $300,000 30-year mortgage, increasing the interest rate from 6.0% to 7.0% increases your monthly payment from $1,798.65 to approximately $1,995.91. That extra $197.26 per month amounts to over $71,000 in additional interest charges over the life of the loan.