What Makes Up a FICO Score? The Five Factors, Explained
Where this information comes from
Scoring formulas are proprietary, but the developer of the FICO score publishes the categories its model weighs and their approximate weightings in What's in Your FICO Score. That page is the primary source for everything below; this guide is a plain-English walk through it, not a strategy for raising a number.
One caveat the developer itself makes: the weightings are averages. For people with short or thin credit files, the model leans on the categories differently. Treat the percentages as a map of emphasis, not a formula you can compute at home.
Payment history — about 35%
The largest category, per myFICO, is whether accounts have been paid as agreed. This reads directly off the month-by-month payment records in your credit report — the same grids you can inspect yourself on your free bureau reports. Because this factor is pure report data, a reporting error here (a payment marked late that wasn't) affects the score's biggest input, which is one reason the dispute process matters.
Amounts owed — about 30%
The second-largest category concerns how much of your available credit is in use — balances relative to limits, sometimes called utilization, along with amounts owed across account types. Note what this is not: it is not your income or your net worth, neither of which appears in a credit report at all. The model can only weigh what the file contains.
Length of credit history — about 15%
This category looks at how long accounts have existed — the age of the oldest, the newest, and the average, and how long since accounts were used. It's the one factor that is purely a function of time, which is why two people with identical habits can score differently if one's file is a decade older.
New credit — about 10%
Recent applications and recently opened accounts make up this category. The relevant report section is the hard-inquiries list. Your own report checks are soft inquiries and, per the FTC, pulling your own free reports does not involve a credit application at all — so reviewing your file is not counted against you here.
Credit mix — about 10%
The smallest category considers the variety of account types in the file — revolving accounts like cards alongside installment accounts like auto loans or mortgages. myFICO describes this as one input among many, not a requirement to hold any particular product.
How to read all this sensibly
Three takeaways keep the factors in perspective. First, every factor is computed from the credit report, so the report is the thing worth reading — the score merely summarizes it. Second, FICO is one family of models among several; a number from a different model weighs things its own way, which is why numbers from different apps disagree. Third, none of this is a to-do list. If you're weighing actual borrowing or debt decisions, that's a conversation for a professional — the National Foundation for Credit Counseling is the major nonprofit network for accredited counseling.
For the difference between the file and the number in the first place, see credit report vs. credit score.