--- title: "How to Calculate Your Monthly Mortgage Payment" site: ProCalc.ai type: Blog Post category: how-to domain: Finance url: https://procalc.ai/blog/how-to-calculate-monthly-mortgage-payment markdown_url: https://procalc.ai/blog/how-to-calculate-monthly-mortgage-payment.md date_published: 2026-03-07 date_modified: 2026-03-27 read_time: 7 min tags: mortgage calculator, monthly payment, home buying, loan amortization, mortgage formula --- # How to Calculate Your Monthly Mortgage Payment **Site:** [ProCalc.ai](https://procalc.ai) โ€” Free Professional Calculators **Category:** how-to **Published:** 2026-03-07 **Read time:** 7 min **URL:** https://procalc.ai/blog/how-to-calculate-monthly-mortgage-payment > *This file is served for AI systems and search crawlers. Human page: https://procalc.ai/blog/how-to-calculate-monthly-mortgage-payment* ## Overview Walk through the actual mortgage payment formula with real numbers, see how rates and terms change your costs, and calculate yours instantly. ## Article I Stared at That Number for Way Too Long I remember sitting at my kitchen table with a pre-approval letter that said I could borrow up to 380,000 and honestly having no clue what that would actually cost me each month. The lender had thrown out a number โ€” something like 2,400 a month โ€” but I couldn't figure out how they got there. I tried plugging things into random websites and each one gave me a slightly different answer, and I started wondering if anyone actually understood this stuff or if we were all just trusting whatever number popped up on screen. Turns out, the math isn't that bad once someone explains it like a normal person. So that's what I'm going to do here. I'll walk through the actual formula, show you a worked example with real-ish numbers, and give you a table so you can see how different rates and loan terms change your payment. And if you just want the answer fast, I built a mortgage payment calculator that does all of this instantly. The Formula (It Looks Worse Than It Is) ๐Ÿ’ก THE FORMULA M = P ร— [ r(1 + r)^n ] / [ (1 + r)^n โ€“ 1 ] M = your monthly payment (principal + interest only) P = the loan principal (how much you're borrowing) r = monthly interest rate (annual rate รท 12) n = total number of monthly payments (loan term in years ร— 12) Yeah, I know. It looks like something from a textbook you'd rather not open. But the thing is, once you plug in your numbers, it's really just multiplication and division. The exponent part โ€” the (1 + r)^n โ€” is the only piece that makes it annoying to do by hand, and that's what calculators are for. Let me walk through a real example. Say you're buying a house for 350,000 and putting 70,000 down (that's 20%, which means you dodge PMI โ€” more on that in a sec). Your loan amount is 280,000. You lock in a 30-year fixed rate at 6.75%. Here's the step-by-step: Convert the annual rate to monthly: 6.75% รท 12 = 0.5625%, or 0.005625 as a decimal Figure out total payments: 30 years ร— 12 = 360 months Calculate (1 + r)^n: (1.005625)^360 = roughly 7.5017 โ€” I used a calculator for this, obviously Plug into the formula: 280,000 ร— [0.005625 ร— 7.5017] / [7.5017 โ€“ 1] Numerator: 280,000 ร— 0.04220 = about 11,815.7 Denominator: 6.5017 Monthly payment: 11,815.7 รท 6.5017 = roughly 1,817 So your principal and interest payment lands around 1,817 per month. That's before taxes, insurance, and any HOA fees get tacked on โ€” which is why your actual mortgage bill will be higher. I've seen people get surprised by an extra 400-600 a month in escrow charges alone. If you want to skip the arithmetic, just use our monthly mortgage calculator and it'll spit out the number in about two seconds. How Rate and Term Change Everything This is the part that really messed with my head when I was shopping for a loan. A half-percent difference in rate sounds like nothing. It is not nothing. Loan Amount Rate Term Monthly Payment (P&I) Total Interest Paid 280,000 6.25% 30 years ~1,724 ~340,640 280,000 6.75% 30 years ~1,817 ~373,920 280,000 7.25% 30 years ~1,911 ~407,960 280,000 6.75% 15 years ~2,478 ~166,040 280,000 6.75% 20 years ~2,120 ~228,800 Look at the difference between 6.25% and 7.25% on a 30-year loan. That's about 187 more per month and over 67,000 more in total interest over the life of the loan. For one percentage point! And then look at what happens when you switch from 30 years to 15 years at the same rate โ€” your monthly payment jumps by about 660, but you save over 207,000 in interest. That's a staggering amount of money. This is why I always tell people to run the numbers on a loan comparison calculator before they commit to anything. The monthly payment matters, sure, but the total cost of the loan is where the real story is. The Stuff the Formula Doesn't Include That formula up there? It only covers principal and interest. Your actual mortgage payment โ€” the one that hits your bank account โ€” usually includes a few more line items bundled into what lenders call PITI: Principal & Interest โ€” the formula part Property Taxes โ€” varies wildly by location (I've seen anywhere from 100 to 800+ per month) Homeowner's Insurance โ€” typically in the ballpark of 100-250 per month PMI โ€” if your down payment is less than 20%, expect to add roughly 0.5-1% of the loan amount per year, divided by 12 On that 280,000 loan example, if you only put 5% down (so you're borrowing about 332,500 instead), PMI alone could add 140-275 per month on top of everything else. That adds up fast. You can estimate this with our down payment calculator to see how different down payment amounts affect your total monthly obligation. And if you're trying to figure out whether you can actually afford the house โ€” not just qualify for the loan, but comfortably afford it โ€” I'd recommend checking our debt-to-income ratio calculator too. Most financial advisors suggest keeping your total housing costs under 28% of gross monthly income, though honestly I think even that feels tight for a lot of people. A Quick Note on Paying Extra One thing that blew my mind when I finally built a spreadsheet for my own mortgage: even small extra payments make a huge difference over time. On that 280,000 loan at 6.75% for 30 years, adding just 200 per month to your payment shaves off about 7 years and saves you roughly 95,000 in interest. Two hundred bucks! If you're curious about your own situation, play around with our extra mortgage payment calculator โ€” it'll show you exactly how much time and money you save. And for the bigger picture of what you can realistically borrow based on your income and debts, there's also the home affordability calculator which I honestly wish I'd used before I started house shopping instead of after. Does the mortgage payment formula include property taxes and insurance? Nope. The standard formula (M = P ร— [r(1+r)^n] / [(1+r)^n โ€“ 1]) only calculates principal and interest. Property taxes, homeowner's insurance, and PMI are separate. Your lender rolls them into one monthly payment through an escrow account, but they're not part of the math formula itself. How much does one extra mortgage payment per year save? On a 280,000 loan at 6.75% over 30 years, making one extra payment per year (about 1,817) could cut roughly 4-5 years off your loan and save you somewhere around 60,000-70,000 in interest. The exact savings depend on when you start making extra payments โ€” earlier is better, since more of your early payments go toward interest anyway. What's the difference between a fixed-rate and adjustable-rate mortgage payment? With a fixed-rate mortgage, your principal and interest payment stays the same for the entire loan. With an adjustable-rate mortgage (ARM), you typically get a lower rate for an introductory period โ€” say 5 or 7 years โ€” and then it adjusts periodically based on market rates. Your payment could go up or down. I personally prefer the predictability of fixed-rate, but ARMs can make sense if you're confident you'll sell or refinance before the adjustment period kicks in. --- ## Reference - **Blog post:** https://procalc.ai/blog/how-to-calculate-monthly-mortgage-payment - **This markdown file:** https://procalc.ai/blog/how-to-calculate-monthly-mortgage-payment.md ### AI & Developer Resources - **LLM index:** https://procalc.ai/llms.txt - **LLM index (full):** https://procalc.ai/llms-full.txt - **MCP server:** https://procalc.ai/api/mcp - **Developer docs:** https://procalc.ai/developers ### How to Cite > ProCalc.ai. "How to Calculate Your Monthly Mortgage Payment." ProCalc.ai, 2026-03-07. https://procalc.ai/blog/how-to-calculate-monthly-mortgage-payment ### License Content ยฉ ProCalc.ai. Free to reference and cite. Do not republish in full without attribution.