What Is a Variable Interest Rate?

A variable interest rate is an interest rate that changes over time. The fluctuations reflect changes in the market, and they differ depending on the lender you choose. If you agree to a loan or line of credit with a variable interest rate, you know that your repayments will go up and down over the lifetime of the loan.

How Is a Variable Interest Rate Calculated?

To calculate the interest on a variable interest rate loan, the lender will use the following formula:

Interest = (Principal x Interest Rate x Number of Periods) / Number of Periods per Year

The main difference between calculating interest on a fixed interest rate loan and a variable interest rate loan is that the interest rate used in the formula may change over time. The lender will typically use an index, such as the prime rate, to determine the interest rate for a variable interest rate loan. The lender will then add a margin to this index to determine the actual interest rate on the loan.

Here’s an example:

Let’s say an ecommerce seller takes out a credit card with a variable interest rate. The interest rate on the credit card is based on the prime rate, which is currently 5%. The credit card issuer adds a margin of 3% to the prime rate, so the actual interest rate on the credit card is 8%.

The ecommerce seller charges $1,000 on their credit card and makes a minimum payment of $25 per month. The term of the loan is 12 months, and the number of periods per year is 12.

Using the formula above, the interest on the credit card balance would be calculated as follows:

Interest = ($1,000 x 8% x 12) / 12 = $80

This means that the total amount of interest the ecommerce seller would pay over the term of the loan would be $80. In addition to the interest, the ecommerce seller would also need to make monthly payments to pay off the principal balance of the credit card. In this example, the minimum monthly payment would be $25, so the ecommerce seller would need to make a total of $1,080 in payments to pay off their credit card balance (including the $80 in interest).