To calculate the monthly payment of your mortgage is the most basic calculation in terms of mortgage. You can apply the same calculation for loans. That is why mortgage monthly payment calculator is also called loan payment calculator. To be safe, make sure you stay below forty percent of your net income. For example, 40% of $4,000 comes to $1,440 mortgage payment.

Here is the mortgage monthly payment formula:
payment = [P(1 + r)n r]/[(1 + r)n - 1]

Here are the amounts that you need:
- P means principal amount of loan.
- r means interest rate. To get the rate divide the interest rate by twelve months, because there are twelve months in year.
- n means the number of payments. Basically, multiply number of years by twelve months.

Suppose you want to know the monthly payment for a 30 year mortgage for $100,000 at 7% interest rate. Rate equals .00583 which is interest rate divide by twelve months, while number of payments equals 360 (30 years X 12 months). You pay $665 mortgage monthly payment per month.

Here is the actual calculation:
Payment equals [$100,000(1 + .00583)360 x 0.00583] / [(1 + 0 .00583)360 - 1]. Your monthly mortgage payment comes to $665.30. By the way, 360 is an exponent.