Your monthly mortgage payment is principal and interest, plus a twelfth of your yearly property tax and home insurance. At Freddie Mac's latest 30-year average of 7.03%, principal and interest on a $320,000 loan come to $2,135.42.
That's a $400,000 home bought with 20% down, and it's the example used below. HOA dues go on top, and so can mortgage insurance if you put down less. Starting from your income instead? The home affordability calculator works backwards to a price.
Which rate goes in the rate box?
Type in the interest rate, not the APR. The Consumer Financial Protection Bureau (CFPB) calls the APR a broader measure of what borrowing costs. It folds points, broker fees and other charges into the rate, so it would overstate your payment.
Your Loan Estimate shows the interest rate on page 1, under "Loan Terms". The APR is on page 3.
No quote yet? Freddie Mac's weekly survey makes a fair benchmark. For the week of September 24, 2026, it put the 30-year fixed at 7.03% and the 15-year at 6.42%. Those averages are for borrowers with 20% down and excellent credit. If your deposit or credit differs, your quote may too.
How much the rate and the term change the bill
Here's the same $320,000 loan at three of the survey's averages:
| Loan on $320,000 | Rate | Principal and interest a month | Total interest |
|---|---|---|---|
| 30-year fixed, a year earlier | 6.30% | $1,980.71 | $393,057 |
| 30-year fixed, now | 7.03% | $2,135.42 | $448,751 |
| 15-year fixed, now | 6.42% | $2,773.49 | $179,228 |
A year ago, the 30-year average was 6.30%. On this loan, today's rate costs $154.71 more a month and $55,694 more interest over 30 years.
The term matters even more. The 15-year loan costs $638.07 more a month, but its total interest is $269,523 lower. You pay less for two reasons: a lower rate and half as many years of interest.
Why the balance barely moves at first
P is the amount you borrow and n the number of monthly payments. The monthly rate, i, is the yearly rate divided by 12.
Interest is charged on whatever you still owe. In month one, that's $320,000 × 7.03% ÷ 12 = $1,874.67. So only $260.75 of your first $2,135.42 payment reduces the debt. The split tilts toward principal slowly, as the balance shrinks.
Less than 20% down? PMI isn't in this number
With under 20% down on a conventional loan, you might need private mortgage insurance (PMI), the CFPB says. It protects the lender, not you. It's billed monthly with your payment, upfront at closing, or both. This calculator leaves it out, so use the PMI calculator to estimate that extra line.
PMI has an end date, set against the home's original value. Once your balance is scheduled to fall to 80%, you can ask your servicer to cancel it. At 78%, it must end automatically, as long as you're current on payments.
Say you put 10% down on the same $400,000 home and borrow $360,000 at 7.03%. Here's how slowly that balance falls:
| Payments made | Balance left | Principal repaid |
|---|---|---|
| 1 year | $356,364 | $3,636 |
| 5 years | $338,982 | $21,018 |
| 8 years | $322,345 | $37,655 |
| 9 years | $315,975 | $44,025 |
| 10 years | $309,142 | $50,858 |
After five years of payments, you've repaid just $21,018. The 80% mark is $320,000, which you pass during year 9. The 78% mark, $312,000, comes during year 10. Pay extra, and you can ask to cancel as soon as your actual balance hits 80%.
Taxes and insurance: the part that can change
Many lenders require you to pay property tax and insurance through an escrow account. A slice of each monthly payment goes into it. Both bills can change from year to year, the CFPB notes, and your total payment moves with them. So a fixed rate fixes only the principal and interest.
The calculator divides the yearly amounts you enter by 12. Enter a $4,800 tax bill, and it adds $400 a month. Its "Total of payments" counts only the loan and its interest, though. Over 30 years, that $400 a month adds $144,000 that the total leaves out.
What an extra $200 a month buys
The extra-payment field shows what paying ahead does. In the calculator, every extra dollar comes straight off the principal, so it stops accruing interest. Here's the $320,000 loan at 7.03% again:
| Extra each month | Monthly outlay | Paid off in | Total interest |
|---|---|---|---|
| $0 | $2,135.42 | 30 yr | $448,751 |
| $100 | $2,235.42 | 26 yr 1 mo | $378,036 |
| $200 | $2,335.42 | 23 yr 2 mo | $328,936 |
| $500 | $2,635.42 | 17 yr 9 mo | $240,581 |
An extra $200 a month saves $119,815 in interest and clears the loan almost seven years early. Now compare the $500 row with the 15-year loan above. For $138.07 more a month, the 15-year cuts another $61,353 of interest, thanks to its lower rate and shorter payoff.
Extra payments win on flexibility, because you can stop them in a tight month. Paying every two weeks is another way to prepay, and the bi-weekly mortgage payment calculator shows that route.
Points, fees and rate resets sit outside the payment
Points and fees you pay to get the loan never appear in the monthly figure. They're folded into the APR instead, which is why the APR usually sits above the rate.
The calculator also applies one rate for the whole term. That fits a fixed-rate loan. With an adjustable rate, read the result as your payment before the first reset.
Sources
- Freddie Mac, Mortgage Rates Average 7.03% (Primary Mortgage Market Survey, September 24, 2026)
- CFPB, What is the difference between a mortgage interest rate and an APR?
- CFPB, What is private mortgage insurance?
- CFPB, When can I remove private mortgage insurance (PMI) from my loan?
- CFPB, What is an escrow or impound account?