Calculate monthly mortgage payment
A=monthly mortgage payment
P=amount borrowed
r=annual interest rate(decimal)
n=the total number of monthly payments

5.5% interest
30 year mortgage
$100,000 amount borrowed P=100,000 r=5.5 n=360 P(1+r/12)n x r/12 ----------------- =A (1+r/12)n -1 2. Originally Posted by SAK1231 Calculate monthly mortgage payment A=monthly mortgage payment P=amount borrowed r=annual interest rate(decimal) n=the total number of monthly payments 5.5% interest 30 year mortgage$100,000 amount borrowed

P=100,000
r=5.5
n=360

P(1+r/12)n x r/12
----------------- =A
(1+r/12)n -1
If you are not coming up with the right answer it's because r must be in decimal form. As a percent, numbers are automatically multiplied by 100 to obtain the percentage. Example: 3/4=.75=75%. Therefore, 5.5% is actually equal to .055.