It's a conundrum wrapped in riddle twisted in an enigma. How is your credit score calculated? The number itself is important. It's a representation of the likelihood that you will repay your debts. Lenders use it to evaluate your creditworthiness. The FICO Score model for your credit score, was created in 1989 by Fair, Isaac and Company and based on consumer credit files from Experian, Equifax and TransUnion, the three national credit bureaus. But the exact algorithm is a bit more complicated. Your payment history, credit utilization ratio, length of credit history and types of credit used are all ingredients into your overall creditworthiness. Take a closer look.