Mortgage Payment Calculator
Enter your loan amount, rate and term to see your monthly principal and interest payment, the total interest you will pay, and what the loan costs you overall.
Your details
What this mortgage calculator works out
This calculator turns three numbers into the figure that actually matters: what you will hand over every month. It uses the standard amortisation formula that lenders use, so the principal and interest portion matches what a loan officer would quote you for the same amount, rate and term.
The headline payment is principal and interest only unless you fill in the optional fields. Add your property tax, home insurance and any HOA dues and the calculator produces your full PITI figure, which is the number a mortgage lender actually assesses when deciding how much you can afford. Property tax and insurance are usually collected monthly into an escrow account and paid on your behalf once or twice a year, which is why they belong in a realistic monthly budget even though they are not part of the loan itself.
The calculator also reports the total interest you will pay across the whole term. This is the single most useful number for comparing offers, because two loans with the same rate but different terms can differ by hundreds of thousands of dollars. On a 300,000 dollar loan at 6.5 percent, moving from a 30-year term to a 15-year term cuts total interest from roughly 382,600 dollars to about 170,400 dollars. The payment rises substantially, so the trade-off is real, but seeing both figures side by side is the only way to judge it honestly.
Bear in mind what is deliberately excluded. The calculator does not model mortgage insurance premiums if you put down less than 20 percent, closing costs, discount points, prepayment penalties or lenders' origination fees. A lender's official Loan Estimate is the authoritative document for those. Treat this as a planning tool that tells you the shape and scale of the commitment before you start talking to lenders.
The formula behind the payment
Monthly principal and interest comes from the standard amortisation formula, the same one lenders use to build your repayment schedule.
| Symbol | Meaning |
|---|---|
A |
Payment per period (your monthly principal and interest) |
P |
Principal, the amount actually borrowed |
i |
Periodic interest rate: the annual rate divided by 12 |
n |
Total number of payments: the term in years multiplied by 12 |
This uses the nominal rate convention, dividing the quoted annual rate by the number of payments per year. That matches how US lenders quote and calculate mortgages, so your figures will agree with the lender's own statement.
Worked example
A 300,000 dollar loan at 6.5 percent over 30 years, which is a typical first-time buyer scenario.
| Figure | Result |
|---|---|
| Monthly payment (principal and interest) | $1,896.20 |
| Interest paid in month 1 | $1,625.00 |
| Principal repaid in month 1 | $271.20 |
| Balance after month 1 | $299,728.80 |
| Interest paid in month 12 | $1,608.40 |
| Principal repaid by month 12 | $3,353.18 |
| Total interest over 30 years | $382,633.47 |
| Total of all payments | $682,633.47 |
In the first year you pay roughly 18,600 dollars and reduce the balance by only about 3,350 dollars. That is not a trick of the calculator, it is how amortisation works: interest is charged on the outstanding balance, so the balance barely moves while it is at its largest. It also explains why extra payments made early are worth far more than the same money paid later.
Estimates only. Your lender's figures may differ because of fees, escrow and rounding.
How to get a better mortgage payment
Attack the balance in the first years
Interest is charged on what you still owe, so an extra 200 dollars a month during year one removes far more total interest than the same 200 dollars a month in year twenty. On this example loan, 200 dollars extra every month retires the mortgage about seven years early and saves around 103,400 dollars.
Ask about an accelerated biweekly plan
Paying half your monthly payment every two weeks means 26 half-payments a year, which is 13 full payments instead of 12. On this loan that shortens the term to about 24 years and two months and saves roughly 88,100 dollars in interest, without ever feeling like a larger monthly commitment.
Compare total interest, not just the payment
A 15-year loan at the same rate costs about 1,100 dollars a month more but saves over 212,000 dollars in interest. Whether that is worth it depends on whether the higher payment still leaves you with an emergency fund and room to save for retirement.
Do not borrow the maximum you are offered
Lenders qualify you on ratios and credit score, not on whether the payment leaves you able to live. A loan that consumes more than about a third of your gross income leaves very little margin when a roof, a boiler or a job change arrives.
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Frequently asked questions
Does this payment include property tax and insurance?
Only if you enter them. The principal and interest figure is always included. Leave the tax and insurance fields at zero and the payment is the loan repayment alone. Fill them in and the calculator shows your full PITI figure, which is the realistic monthly cost of owning the home.
Why is so little principal repaid at the start?
Interest is calculated on the outstanding balance, which is at its highest on day one. With a 6.5 percent rate on 300,000 dollars, the first month's interest alone is 1,625 dollars, leaving only about 271 dollars of your 1,896 dollar payment to reduce the balance. As the balance falls, the interest share shrinks and the principal share grows.
Should I choose a 15-year or a 30-year term?
A 15-year term costs far less in total interest and builds equity quickly, but the payment is substantially higher. A 30-year term keeps the required payment low, and you can always pay extra to behave like a 15-year loan while keeping the flexibility to stop. Many borrowers take the 30-year term and make extra payments, which is the more forgiving choice.
How accurate is this compared with my lender's quote?
The principal and interest figure should match to within a few cents for the same inputs. Differences usually come from fees financed into the loan, discount points, mortgage insurance, or a different day-count convention. Your lender's Loan Estimate is the authoritative version.
Does a bigger down payment lower my monthly payment?
Yes, because you borrow less. Enter the down payment and reduce the loan amount by the same figure to model it. Putting down at least 20 percent also usually avoids mortgage insurance, which can add several hundred dollars a month that does not reduce your balance at all.