How to use this mortgage calculator
- Enter the Home price and your Down payment in dollars or as a percent (the boxes stay in sync).
- Pick a Loan term (15, 20 or 30 years, or Custom up to 50) and type the Interest rate from your Loan Estimate.
- Set the First payment month and year so the schedule shows real dates.
- Under Taxes, insurance, PMI and HOA, enter property tax (percent of price or dollars a year), yearly insurance, a PMI rate and HOA dues.
- Add Extra principal per month to see the new payoff date and interest saved. The schedule switches between Yearly and Monthly and downloads as a CSV file.
How the payment is calculated
Principal and interest use the standard fixed-rate amortization formula:
M = P × r(1 + r)n / ((1 + r)n − 1)
P is the loan amount (price minus down payment), r is the yearly rate divided by 12 and n is the number of monthly payments. Tax and insurance are divided by 12, as in an escrow account. Monthly PMI is your PMI rate times the original loan, divided by 12. Under the Homeowners Protection Act rules explained by the CFPB, PMI stops once the scheduled balance reaches 78% of the home price, or at the halfway point of the term if sooner. Extra payments go straight to principal.
Worked example
The calculator opens with a $400,000 home and $80,000 down (20%), which leaves a $320,000 loan. At 7% for 30 years, principal and interest come to $2,128.97 a month. Property tax at 1% of the price adds $333.33 and $1,500 a year of insurance adds $125.00, so the total monthly payment is $2,587.30. There is no PMI because the down payment is 20%. Over 360 payments you pay $446,428.47 in interest. Enter $200 of extra principal and the loan is paid off in 23 years 3 months, saving $118,971.95. The 7% rate is an example, not a quote: Freddie Mac's weekly survey publishes the current 30-year fixed average, and the rate on your own offer is the one to use.
Limits and edge cases
- Fixed-rate loans only; adjustable-rate resets are not modeled.
- Tax, insurance and HOA are held flat, though they usually rise over time.
- Real PMI pricing depends on your credit score and loan-to-value, so 0.5% is a placeholder. FHA mortgage insurance follows different rules.
- Closing costs, points and fees are not included.
Compare two offers side by side with the mortgage comparison tool, work out how much to save first with the down payment calculator, or check whether a new rate pays off with the refinance calculator.
Mortgage calculator FAQ
How much house can I afford?
A common guideline is the 28/36 rule: keep the total housing payment at or below 28% of gross monthly income and all debt payments at or below 36%. Lenders can approve higher ratios. Try prices here until the total monthly payment fits, then check your ratios with the debt-to-income calculator.
When does PMI go away?
On a conventional loan you can ask your servicer to cancel PMI once your balance is scheduled to reach 80% of the home's original value, and it must end automatically at 78% if you are current on payments. It also ends at the midpoint of the loan term. The calculator shows the month PMI stops on your schedule.
Is a 15-year or 30-year mortgage better?
A 15-year loan costs more each month but far less overall. At 7%, a $320,000 loan is $2,128.97 a month over 30 years with $446,428.47 of interest, or $2,876.25 a month over 15 years with $197,725.08 of interest.
Do extra payments really shorten a mortgage?
Yes. Extra principal lowers the balance right away, so each later payment holds less interest. In the example above, $200 more a month ends the loan 6 years 9 months early. Ask your servicer to apply extra amounts to principal and confirm your loan has no prepayment penalty.
Sources: CFPB, removing PMI; Freddie Mac Primary Mortgage Market Survey (weekly 30-year fixed average). Estimates only, not a loan offer. Related reading: how to calculate a mortgage payment by hand.