Home Mortgage Calculator
Enter your home price, down payment, loan term, and interest rate to get your monthly payment and a complete amortization breakdown. Add property taxes, homeowners insurance, PMI, and HOA fees to see your true all-in monthly cost. Include extra payments to see how much interest you save and how early you pay off your loan.
Formula
Worked example
For a $400,000 home with a $80,000 (20%) down payment, a 30-year term at 6.75%: loan = $320,000, monthly rate r = 6.75/12/100 = 0.005625, payments n = 360. Monthly P&I = 320,000 x [0.005625 x 1.005625^360] / [1.005625^360 - 1] = $2,075/month. Total interest over 30 years = $426,985. Paying an extra $200/month reduces total interest by about $71,000 and cuts 4 years off the loan.
How a fixed-rate mortgage payment is calculated
A fixed-rate mortgage uses a standard amortization formula: monthly payment = P x [r(1+r)^n] / [(1+r)^n - 1], where P is the loan amount, r is the monthly interest rate (annual rate divided by 12), and n is the total number of monthly payments. Because the rate and term are fixed, every payment is the same dollar amount, but the split between principal and interest shifts every month. Early payments are heavily weighted toward interest; later payments become mostly principal. This calculator works through that formula with your exact numbers and builds a year-by-year schedule so you can see the shift.
Understanding the true all-in monthly cost
Your lender quotes a principal-and-interest payment, but your real monthly housing cost is higher. Property taxes are typically collected monthly as one-twelfth of the annual bill and held in escrow by the lender. Homeowners insurance is similarly escrowed. If your down payment is below 20%, lenders require Private Mortgage Insurance (PMI), which protects the lender if you default. PMI typically runs 0.3 to 1.5% of the loan amount per year, divided into monthly premiums, and is usually cancelled automatically when your equity reaches 22% of the original value. Homeowners Association (HOA) fees cover shared amenities and maintenance in condos and planned communities. This calculator combines all four into a single all-in monthly figure so you know your actual cash outflow.
How extra payments dramatically shorten your loan
Any payment you make above the required minimum goes directly to principal, not interest. Paying even a small extra amount each month has a compounding effect: a lower principal balance accrues less interest the following month, so more of each future required payment also goes to principal. On a 30-year, $320,000 loan at 6.75%, paying an extra $200 per month can cut roughly 4 years from the loan and save around $70,000 in interest. Paying an extra $500 per month can shorten the term by more than 8 years. The amortization schedule and chart in this calculator show you exactly how the balance declines with and without extra payments.
Fixed-rate vs. adjustable-rate mortgages
This calculator solves for a fixed-rate mortgage (FRM), where the interest rate stays constant for the entire loan term. The 30-year fixed and 15-year fixed are the most common home loan products in the US. Adjustable-rate mortgages (ARMs) start with a lower fixed rate for an introductory period (3, 5, 7, or 10 years) and then reset periodically based on a market index such as SOFR. ARMs can be cheaper initially but carry rate risk after the fixed period ends. If you are comparing an ARM to a fixed-rate loan, run this calculator with the fully indexed rate scenario to stress-test the worst case.
Down payment and PMI guide
| Down Payment | Loan-to-Value | PMI Required? | Typical PMI Cost |
|---|---|---|---|
| Less than 3% | Over 97% | Yes | 1.0-1.5% per year |
| 3-4.9% | 95-97% | Yes | 0.9-1.3% per year |
| 5-9.9% | 90-95% | Yes | 0.7-1.1% per year |
| 10-14.9% | 85-90% | Yes | 0.5-0.9% per year |
| 15-19.9% | 80-85% | Yes | 0.3-0.6% per year |
| 20% or more | Below 80% | No | None |
How your down payment percentage affects mortgage requirements and costs.
Frequently asked questions
How is my monthly mortgage payment calculated?
Your principal-and-interest payment is calculated using the amortization formula: P x [r(1+r)^n] / [(1+r)^n - 1], where P is the loan amount, r is the monthly interest rate (annual rate divided by 12), and n is the total number of payments. This calculator applies the formula instantly with your numbers. Your actual monthly cost also includes property taxes, homeowners insurance, PMI (if applicable), and HOA fees.
What is PMI and when can I get rid of it?
Private Mortgage Insurance protects the lender if you stop making payments. It is required when your down payment is less than 20% of the home price. PMI typically costs 0.3 to 1.5% of the loan amount per year, added to your monthly payment. Under the Homeowners Protection Act, lenders must automatically cancel PMI once your loan balance reaches 78% of the original purchase price on schedule. You can request cancellation earlier if you can prove your equity has reached 20% through appreciation or extra payments.
Should I choose a 15-year or 30-year mortgage?
A 30-year mortgage has a lower monthly payment, freeing cash flow for other goals, but you pay roughly twice as much total interest over the life of the loan. A 15-year mortgage has a higher monthly payment (often 30-40% higher) but dramatically less interest and you build equity faster. A useful middle path is to take the 30-year loan but make extra payments when cash flow allows. You get the flexibility of the lower required payment but can replicate the 15-year outcome in good months.
How much do extra monthly payments save?
Extra payments go entirely to principal, which lowers the balance that accrues interest. The savings compound over time. On a typical 30-year loan the interest savings from consistent extra payments can reach tens of thousands of dollars. Use the "Extra Monthly Payment" field in this calculator and watch the interest saved and payoff time update in real time.
What costs are not included in this calculator?
This calculator covers the core recurring costs: principal, interest, taxes, insurance, PMI, and HOA. It does not include one-time closing costs (typically 2-5% of the loan amount), home inspection fees, appraisal fees, or moving costs. It also does not model the tax deductibility of mortgage interest (which depends on whether you itemize deductions) or changes in property tax or insurance rates over time.
How does the amortization schedule work?
An amortization schedule lists every payment from the first to the last, showing how much goes to interest and how much to principal each period. Early in the loan, most of each payment is interest because the outstanding balance is high. As the balance falls, the interest portion shrinks and the principal portion grows. The schedule table in this calculator shows annual summaries, and the chart shows the declining balance over the entire loan term.