APR stands for annual percentage rate. It is a calculation that determines the annual interest you will pay on a loan or a line of credit. Knowing how to calculate APR is a useful skill that can help you determine the amount of interest you will pay. APR is determined by the amount and the terms of your loan. You may calculate the interest either manually or with a free online APR calculator.

### Things You'll Need

- Calculator

- Free APR online calculator

Educate yourself about APR. Know the basics such as APR being interest that is applied yearly to loans for cars, mortgages and lines of credit.

Know the terms of your loan. For instance, a loan with a 6 percent APR means that you will pay $6 each year for every $100 you owe.

Use a free online calculator to determine the APR of your loan. According to the Efunda APR calculator, a $20,000 loan with a 6 percent APR, no extra costs and a 12-month loan term will have $655.94 in total interest. The total amount paid on the loan when the term ends will be $20,655.94.

Use the APR equation to calculate the APR of your loan. Using the above loan example, multiply the loan amount ($20,000) by the interest rate (6 percent). Divide that amount by the term of the loan (12 months) to calculate the monthly APR amount. Your equation should look like this: (20,000 x 0.06) / 12 = $100 APR.