Mortgage Payment Calculator
A mortgage payment calculator turns three numbers, the loan amount, the interest rate and the term, into the single figure most home buyers care about: the monthly principal and interest. This tool uses the standard amortization formula that every fixed-rate lender relies on, so the payment it shows is the level amount that fully repays the loan over the term you choose while covering the interest charged each month. It also reports the total of all payments and the total interest you will pay over the life of the loan, which makes the true cost of borrowing clear rather than hidden behind a comfortable monthly figure. Enter your own loan amount, rate and term to compare options, test a 15-year against a 30-year term, or see how a higher rate lifts both the payment and the lifetime interest. The payment shown here is principal and interest only; your full housing cost can also include property taxes, homeowners insurance, mortgage insurance and association dues, which the US Consumer Financial Protection Bureau recommends budgeting for separately. Every figure is computed deterministically from the formula shown in full below, with a worked example that reconciles exactly to the calculator so you can follow each step and trust the result.
A fixed mortgage payment is M = P r (1+r)^n / ((1+r)^n - 1). A $300,000 loan at 6.5% over 30 years costs $1,896.20 a month, $382,633.47 in total interest.
Mortgage payment formula
M = P * r * (1 + r)^n / ((1 + r)^n - 1)
M = monthly payment (principal and interest)
P = loan amount (principal)
r = monthly interest rate = annual rate / 100 / 12
n = number of monthly payments = years * 12
The monthly rate r is the annual rate divided by 12, and n is the term in months. The payment M is the level amount that repays the whole balance over n months. Total of payments is M multiplied by n, and total interest is that total minus the original loan amount.
Worked example
A 300,000 loan at an annual rate of 6.5% over 30 years. First convert the rate and term: r = 0.065 / 12 = 0.00541667 per month, and n = 30 * 12 = 360 months.
- Growth factor: (1 + r)^n = (1.00541667)^360 = 6.99180
- Numerator: P * r * (1 + r)^n = 300,000 * 0.00541667 * 6.99180 = 11,361.67
- Denominator: (1 + r)^n - 1 = 6.99180 - 1 = 5.99180
- Monthly payment M = 11,361.67 / 5.99180 = 1,896.20
- Total of payments = 1,896.20 * 360 = 682,633.47
- Total interest = 682,633.47 - 300,000 = 382,633.47
The monthly principal and interest payment is 1,896.20, the total of payments is 682,633.47 and the total interest is 382,633.47. These are the calculator's default inputs, so the results above match the widget exactly.
Monthly payment per 100,000 borrowed
Multiply the figure for your rate and term by your loan amount in hundred-thousands. For example, a 300,000 loan at 6.5% over 30 years is about 3 times the 632.07 shown below.
| Annual rate | 15 years | 20 years | 30 years |
|---|---|---|---|
| 5.0% | 790.79 | 659.96 | 536.82 |
| 6.0% | 843.86 | 716.43 | 599.55 |
| 6.5% | 871.11 | 745.57 | 632.07 |
| 7.0% | 898.83 | 775.30 | 665.30 |
| 8.0% | 955.65 | 836.44 | 733.76 |
Figures are monthly principal and interest per 100,000 borrowed. Method: US Consumer Financial Protection Bureau, Owning a Home.
Mortgage payment calculator: frequently asked questions
How is a monthly mortgage payment calculated?
A fixed-rate monthly payment uses the amortization formula M = P times r times (1 + r)^n divided by ((1 + r)^n minus 1). P is the loan amount, r is the monthly interest rate (the annual rate divided by 12), and n is the number of monthly payments (years times 12). The result is the level payment that pays off the loan over the full term while covering the interest charged each month.
Does this include taxes, insurance and HOA fees?
No. This calculator shows principal and interest only, the part set by the loan amount, rate and term. Your full monthly housing cost can also include property taxes, homeowners insurance, mortgage insurance and any homeowners association dues, often collected together in an escrow account. The US Consumer Financial Protection Bureau recommends budgeting for those extra costs on top of principal and interest.
Why does so much of an early payment go to interest?
Interest is charged on the outstanding balance, which is largest at the start. In the first month nearly all of the payment covers interest and only a small slice reduces the balance. As the balance falls, the interest portion shrinks and more of each level payment goes to principal. This is why the total interest over a long loan can be very large.
How does the loan term change the payment?
A longer term spreads the loan over more payments, so each monthly payment is smaller, but you pay more total interest because you owe the balance for longer. A shorter term raises the monthly payment but cuts total interest sharply. Compare a 15-year and a 30-year term in the calculator to see the trade-off between monthly affordability and lifetime cost.
What interest rate should I enter?
Enter the annual percentage rate quoted by your lender for the loan you are considering. Rates depend on the loan type, term, your credit profile and market conditions, so there is no single correct figure. The rate is a fully editable input here. For published average rates and guidance on shopping for a mortgage, see the US Consumer Financial Protection Bureau.
Official sources
- Mortgage basics, monthly payment guidance and the costs of owning a home: US Consumer Financial Protection Bureau, Owning a Home. As at 24 June 2026.
Reviewed by the CalculatorHub team, edited by James Graham, 24 June 2026. See our methodology. This is general information, not financial, tax, legal or investment advice.