About This Calculator
How It Works
This calculator takes your home price, down payment, interest rate, and loan term and computes your monthly principal-and-interest payment using the standard amortization formula. It also layers in property tax and insurance estimates to show your true all-in monthly housing cost — the number that actually matters when you're budgeting. Change any input and you'll immediately see how much the interest rate or term length moves the needle. It's designed for the moment when a house feels right and you need to know if the math agrees.
The Formula
M = P[r(1+r)^n]/[(1+r)^n-1] where P = principal, r = monthly rate, n = number of payments
When to Use This
Use this before making an offer — not after. Knowing your monthly payment range lets you shop with confidence and avoid falling in love with a home that will quietly stress you out for 30 years. It's also useful for comparing a 15-year vs. 30-year term, or for stress-testing what happens if rates are 1% higher than you hoped.
Limitations
This calculator uses a fixed interest rate for the entire loan term — if you're considering an ARM (adjustable-rate mortgage), the actual payments will change over time and this won't capture that. It also can't account for PMI (private mortgage insurance, required if your down payment is under 20%), HOA fees, or the specific property tax assessment in your municipality. Use it for orientation; your lender and real estate agent will have the actual numbers.
Example
A $400,000 loan at 6.5% over 30 years results in monthly payments of about $2,528 — plus $510,178 in total interest. Yes, really.
Did You Know?
The word 'mortgage' comes from Old French meaning 'death pledge.' Cheerful, right? The idea was that the deal 'dies' when the loan is paid off. Or when you give up.
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You've Run the Numbers — Now Make Sure You Understand Them
A mortgage calculator tells you what your monthly payment will be. What it can't tell you is everything else that comes with buying a home — the negotiation tactics, the inspection red flags, the closing cost traps, the mortgage types lenders won't always explain clearly, and the financial decisions that separate buyers who build wealth from buyers who struggle for years after signing.
Most first-time buyers are so focused on finding the right house that they skip the education part. That's expensive. The difference between a well-informed buyer and an uninformed one can easily be $10,000–$30,000 over the life of a purchase — in closing costs they didn't negotiate, in mortgage terms they didn't understand, or in inspection issues they didn't catch.
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Written by the hosts of the BiggerPockets Money Podcast — two people who have collectively bought and sold homes for over thirty years — this is the most practically useful home-buying book on Amazon. It covers everything a calculator can't: how to evaluate whether buying even makes sense for your situation, how to navigate mortgage types and lender negotiations, what to watch for during inspections, and how to avoid the financial pitfalls that catch most first-time buyers off guard. Rated 4.7 stars with nearly 700 verified reviews. Under $16 in paperback — the cheapest insurance you can buy before making a six-figure decision.
If you've just calculated your mortgage payment and you're seriously considering buying — read this before you make an offer.
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