Annual Percentage Rate (APR) is the equivalent interest rate considering all the added costs to a given loan. Naturally, it is a function of the loan amount, the interest rate, the total added cost, and the terms. The APR would equal the interest rate if there is no additional costs to a given loan. Here is an example:
Total money borrowed:

$200,000 
Total extra cost:

$5,000 
Interest rate: 
7.5% 
Term: 
30 years 
To find the monthly payment for this loan, we can use the
Loan Calculator Scenario #1 with $205,000 as the total loan amount
(you are not borrowing this much but you will owe this amount when the loan is closed),
7.5% as the interest rate, and 360 as the number of payments (1 payment/month for 30 years).
The monthly payment is found to be $1,433.39.
Now, since you are only borrowing $200,000 but paying $1,443.39/month for 30 years,
we can backcalculate the equivalent interest rate (APR) by using the
Loan Calculator Scenario #2. The answer is,
Annual Percentage Rate = 7.75%.
The APR Calculator on this page will perform these two calculations in one pass.
