Credit scores are calculated based on a variety of factors and based on information found in your credit report.
For the FICO credit score, which is the most commonly-used scoring model, a credit score for the average consumer is calculated based on the following five factors and weighted by the percentages indicated:
Payment history (35%) - This category measures if you've made on-time payments with credit accounts. Late payments can hurt your credit score.
Amounts owed (30%) - The amount of debt owed factors into this category. Although having some debt isn't always bad for your credit score, using too much of your available credit can lower your score. For example, "maxing out" credit cards can have a negative effect on your credit score.
Length of credit history (15%) - Credit history measures several age-related factors in your credit report. This includes the age of your oldest account, the age of your newest account, the average age of all your accounts, and the date of last activity on accounts. Generally, the longer your credit history, the better for your score.
Types of credit used (10%) - This category grades the types of credit accounts on your credit report, including credit cards, installment loans, a mortgage, and more. A mix of several forms of credit is typically good for your credit score.
New credit (10%) - This includes if you've opened new credit accounts recently, which may indicate a greater risk to potential credit issuers.
Any information on your credit report can be used, although credit scores often place more importance on more recent data.