# Mortgage calculator

> A mortgage payment is the loan amount times the monthly rate, divided by 1 minus (1 + rate)^-months. A $400,000 home with 20% down leaves a $320,000 loan. At an example 6.5% rate over 30 years, principal and interest come to $2,022.62 a month, and total interest reaches $408,142.36. Property tax and insurance estimates add to that monthly figure.

Source: https://www.calterix.com/en-us/simulator/mortgage/ · Updated 11/06/2026 · en-US

## How a mortgage payment works

Most U.S. home loans are fixed-rate: the principal and interest payment stays the same every month. Each payment covers that month's interest first, and whatever is left pays down the loan. Early on, interest takes the biggest bite. Over time the split flips.

```
Monthly rate r = annual rate ÷ 12
Months n = years × 12
Payment = loan × r ÷ (1 − (1 + r)^−n)
```
Example: $320,000 at 6.5% for 30 years. r = 0.065 ÷ 12, n = 360, so the payment is $2,022.62.

Lenders often talk about PITI: principal, interest, taxes, and insurance. The calculator adds the last two as monthly estimates you type in, so the total matches what you would really send each month if taxes and insurance are collected with the loan.

To see every payment, use the [amortization schedule calculator](https://www.calterix.com/en-us/simulator/amortization/). To compare how a payment that shrinks over time differs from a level one, try [fixed payment vs fixed principal](https://www.calterix.com/en-us/simulator/fixed-payment-vs-fixed-principal/).

## Worked examples

| Term | Principal and interest | Total interest | Total paid |
| --- | --- | --- | --- |
| 30 years | $2,022.62 | $408,142.36 | $728,142.36 |
| 20 years | $2,385.83 | $252,600.17 | $572,600.17 |
| 15 years | $2,787.54 | $181,757.84 | $501,757.84 |

$320,000 loan at an example 6.5% rate. Enter your own rate for your numbers.

A shorter term raises the monthly payment but cuts interest a lot. Moving from 30 to 15 years adds $764.92 a month and saves $226,384.52 in interest.

Add $400 a month for property tax and $125 for insurance to the 30-year example and the monthly payment is $2,547.62.

## Payment per $100,000 borrowed

| Rate | 30 years | 20 years | 15 years |
| --- | --- | --- | --- |
| 5.5% | $567.79 | $687.89 | $817.08 |
| 6.0% | $599.55 | $716.43 | $843.86 |
| 6.5% | $632.07 | $745.57 | $871.11 |
| 7.0% | $665.30 | $775.30 | $898.83 |
| 7.5% | $699.21 | $805.59 | $927.01 |

Principal and interest only. Multiply by your loan amount ÷ 100,000. Rates are examples.

A $350,000 loan at 7.0% for 30 years is 3.5 × $665.30 = $2,328.55 a month. A one-point rate change moves the payment by roughly 10% on a 30-year loan.

## Down payment and mortgage insurance

A bigger down payment means a smaller loan, a smaller payment, and less interest. The calculator takes it as a percent or as dollars, whichever you have in mind.

If your down payment is under 20%, lenders often add mortgage insurance, which raises the monthly cost. The amount depends on the loan type, your credit, and the size of the down payment, so the calculator leaves it out. Ask your lender for a quote and add it to the tax and insurance estimate if you want it in the total.

> Property tax and home insurance vary a lot by location and by home. The starting values here are examples. Replace them with numbers from the listing, the county tax bill, or an insurance quote.

## Common mistakes when estimating

- Looking only at principal and interest. Taxes, insurance, and sometimes mortgage insurance can add hundreds of dollars a month.
- Forgetting upkeep. Repairs and maintenance are not part of the payment, so keep a budget for them.
- Using an advertised rate as your rate. Credit, down payment, and loan type change the rate you are offered.
- Choosing the term by payment alone. A 30-year loan has a lower payment, but total interest can be more than the loan itself.
- Counting on a house price you can reach only with a perfect payment. Leave room in the budget for surprises.

Thinking about whether to buy at all? The [rent vs buy calculator](https://www.calterix.com/en-us/simulator/rent-vs-buy/) compares the two paths using assumptions you can change.

## Frequently asked questions

### How do I calculate my monthly mortgage payment?

Multiply the loan by the monthly rate and divide by 1 − (1 + rate)^−months. A $320,000 loan at 6.5% for 30 years works out to $2,022.62 a month for principal and interest, before taxes and insurance.

### How much house can I afford on my income?

Pick the share of income you want to spend on housing, subtract tax and insurance, and see what loan the rest supports. A $120,000 income at 28% gives $2,800 a month, which supports a home around $449,912 at 6.5% with 20% down.

### How much is a mortgage on a $400,000 house?

With 20% down, a 30-year loan at an example 6.5% rate costs $2,022.62 a month for principal and interest. Adding $400 a month for property tax and $125 for insurance brings the total to $2,547.62.

### Should I choose a 15-year or 30-year mortgage?

A 15-year loan has a higher payment but far less interest. On $320,000 at 6.5%, the 15-year payment is $2,787.54 versus $2,022.62, and total interest is $181,757.84 versus $408,142.36. Pick the payment you can carry comfortably.

### What is PMI and does this calculator include it?

PMI is private mortgage insurance. If your down payment is under 20%, lenders often add it to the monthly cost. The calculator does not include it, because the amount depends on your loan and credit. Add your lender's quote to the insurance estimate.

### How much interest will I pay over the life of a mortgage?

Use the Interest by year tab. On $320,000 at 6.5% for 30 years, total interest is $408,142.36, which is about 128% of the amount borrowed.