Mortgage Calculator

A mortgage calculator turns three numbers — loan amount, interest rate, and term — into the single figure that will shape your monthly budget for the next 15 or 30 years. Most buyers underestimate that number by $200 to $400 a month because they forget property taxes and insurance. This guide walks through exactly what goes into a payment, shows a worked example on a $300,000 loan, and explains the rate and term trade-offs that quietly cost borrowers tens of thousands over the life of a loan.

What Goes Into a Mortgage Payment?

Lenders and loan officers call the full monthly payment PITI — shorthand for Principal, Interest, Taxes, and Insurance. The CFPB's loan-options guideuses the same breakdown, and it's the structure every mortgage servicer bills under.

• Principal: The portion that actually reduces your loan balance. In year one of a 30-year loan, principal is only about 15% of each payment — the rest is interest. By year 20, that ratio flips.
• Interest:The cost of borrowing, calculated monthly on the remaining balance. A 6.5% rate means you're paying 0.542% of whatever you still owe each month.
• Taxes:Property taxes, typically escrowed monthly so the lender can pay them directly. Expect 0.5% to 2.5% of the home's value per year, depending on your state and county.
• Insurance: Homeowners insurance (usually $1,200-$2,500/year) plus private mortgage insurance (PMI) if your down payment is under 20%. PMI adds roughly $100-$300 a month on a typical loan. Our homeowners insurance calculator estimates that premium from your dwelling coverage, location, and deductible.

How the Mortgage Formula Works

The fixed monthly payment on an amortizing loan comes from one formula: M = P × [r(1+r)ⁿ] / [(1+r)ⁿ − 1], where P is the principal, r is the monthly interest rate (annual rate ÷ 12), and n is the total number of payments (years × 12). It looks intimidating, but it's just making sure your balance hits exactly zero on the final payment.

What surprises most first-time borrowers is how uneven the split is. Interest is always calculated on the remaining balance, so early payments are mostly interest. If you want to see this in detail for any savings scenario, the same math drives our compound interest calculator— it's the same force, just working for you instead of against you.

A Worked Example: $300K Loan at 6.5%

Plug a $300,000 loan at 6.5% for 30 years into the formula and you get a monthly principal-and-interest payment of about $1,896. Over 360 payments, you pay back $682,633 total — $382,633 of that is pure interest. You will pay more in interest than you originally borrowed. A full mortgage amortization schedule shows exactly how that interest front-loads — your first payment alone puts $1,625 toward interest and only $271 toward principal.

That is before taxes and insurance. Add a modest $3,600 property-tax bill and $1,500 homeowners policy and the full PITI payment climbs to roughly $2,321. If your down payment is under 20%, add $150-$250 more for PMI — our down payment calculator shows exactly how each percentage point changes your monthly cost. And don't forget the one-time closing costs — typically 2-5% of the purchase price — that you'll owe on settlement day on top of everything else.

30-Year vs. 15-Year Mortgage

Same $300,000 loan, same 6.5% rate, different terms. Here's what changes:

The 15-year costs $717 more per month but saves $212,212 in interest. The smarter framing is not "which term is better" but "which payment can you reliably afford without skipping retirement contributions?" A 30-year loan with voluntary extra payments gives you flexibility a 15-year contract does not — the dedicated 30-year mortgage calculator shows exactly how much more house that lower payment lets you buy, while the 15-year mortgage calculator compares both terms at their real split rates and shows how much faster equity builds. For buyers with irregular or bonus-heavy income, an interest-only mortgage offers a third option with a much lower base payment — but it comes with its own trade-offs worth pricing carefully before choosing.

How Interest Rates Affect Your Payment

Rates move weekly. According to Freddie Mac's Primary Mortgage Market Survey, the average 30-year fixed rate has swung more than 400 basis points in the last three years alone. On a $300,000 loan over 30 years, every half-point matters:

• 6.0%: $1,799/mo — $347,515 total interest
• 6.5%: $1,896/mo — $382,633 total interest
• 7.0%: $1,996/mo — $418,527 total interest
• 7.5%: $2,098/mo — $455,153 total interest

A single point between 6% and 7% costs you about $197 per month and over $71,000 across the life of the loan. That's why shopping three to five lenders is not optional — it's the single highest-ROI hour you can spend in a home purchase. If you expect to move within a few years, an adjustable rate mortgage calculator shows how a lower start rate compares against this fixed payment — and what the rate could climb to once the fixed period ends.

Common Mortgage Mistakes to Avoid

• Budgeting only for principal and interest.Taxes, insurance, and HOA fees can easily add 20-35% to your monthly housing cost. The rate advertised on a lender's landing page is not the number you will actually pay. Run the full payment through the mortgage calculator with taxes and insurance to see your true PITI cost, or use the principal and interest calculator to see how little of an early payment actually pays down the loan.
• Putting down less than 20% without running the PMI math. PMI on a low-down-payment loan adds $100-$300/month that builds zero equity. That is $36,000 out the window over ten years on a typical loan. Our PMI calculator shows the monthly cost and the exact month it cancels — or use the mortgage calculator with PMI to see that premium folded into your full payment — while the home equity calculator tracks how quickly you're actually building equity with each payment.
• Fixating on the monthly payment instead of total cost.A 30-year loan "feels" cheap because the monthly number is smaller, but you pay back more than twice the amount you borrowed. Always check the total-interest column — the mortgage interest calculator breaks down exactly how much of that total is interest and how extra payments shrink it. And remember that principal and interest are only part of the picture. The house payment calculator adds maintenance and utilities to show the true monthly cost of owning the home.
• Shopping only one lender. Rate spreads of 0.25%-0.50% between lenders on the same day are normal. On a $300,000 loan, that gap is $15,000-$35,000 over 30 years.

Tips for Getting the Best Mortgage Rate

• Push your credit score above 740. The biggest rate tier breaks sit at 620, 680, 740, and 780. Moving from 720 to 740 can shave 0.125%-0.25% off a conventional rate.
• Request a Loan Estimate from at least three lenders on the same day.Rates move daily; quotes from different days are not comparable. Federal rules require lenders to issue a standardized Loan Estimate within three business days.
• Consider discount points only if you'll hold the loan 5+ years.One point (1% of the loan) typically drops the rate about 0.25%. Divide the point cost by your monthly savings to find the break-even — if you'll sell or refinance before then, skip it.
• Lock once you're under contract. Most lenders offer 30 to 60-day locks at no charge. Unlocked rates can drift 0.25% in a single week of market volatility.
• Check what you can actually afford first. Run the numbers on our home affordability calculator before you talk to a lender — it uses the 28/36 DTI rule to show a safe price range based on your income and debts. Walking in with a target payment makes the conversation much shorter.

When to Use This Calculator

• Starting a home search and need to know your realistic price range
• Comparing Loan Estimates from multiple lenders side-by-side
• Deciding between a 15-year and 30-year term
• Checking the monthly-payment impact before making an offer
• Planning a refinance and want to see the payment at a new rate — the mortgage refinance calculator adds the break-even month and closing-cost math
• Eligible for a VA loan and want to compare a zero-down, no-PMI payment against this conventional estimate
• Considering a home equity loan or HELOC and need to see how the second payment stacks on top of your first mortgage