FICO® Score

A FICO® Score is a credit score built by Fair Isaac Corporation and calculated from the information in one of your credit reports. Fair Isaac does not collect the underlying data or maintain a file on you. It builds the models and licenses them to the three nationwide credit bureaus, each of which runs a model against the report it holds, which is why you have more than one FICO Score at any moment rather than a single number. Base FICO Scores are reported on a 300 to 850 scale, with higher numbers indicating lower predicted risk. Fair Isaac states that its scores are the most widely used in the United States and that 90% of top lenders rely on them.

The name and the category are worth separating, because the two are used interchangeably and are not the same thing. A credit score is any number a model derives from a credit file, a category that also includes VantageScore and scores lenders build for their own use. A FICO Score is specifically one produced by a Fair Isaac model. The words blur together because Fair Isaac's models dominate the market, and the distinction only bites at the moment it matters most, when a score you have been watching for free turns out to be a VantageScore and is therefore not the number a lender will price your loan against. FICO is a registered trademark of Fair Isaac Corporation.

The score is derived entirely from credit report data, grouped by Fair Isaac into five categories with published weights: payment history (35%), whether you have paid past accounts on time, which Fair Isaac names as the single most important factor; amounts owed (30%), dominated by how much of your available revolving credit you are using; length of credit history (15%), including the age of your oldest account, your newest, and the average; new credit (10%), the pace at which you have opened accounts recently; and credit mix (10%), whether you have handled both revolving and installment debt. Fair Isaac attaches a caveat worth carrying: those percentages describe how important each category is for a typical profile, and the importance can differ from one person to another, since a score for someone with a short file is calculated differently from one for a long history.

You do not have "a" FICO Score, you have a grid of them. Fair Isaac has released successive versions as borrowing behavior changed, and lenders adopt new versions on their own timetables or not at all. FICO Score 8 is the most widely used version, FICO Score 9 is also in broad use, and the FICO Score 10 suite is the newest, with FICO Score 10T adding "trended" data, meaning the pattern of your balances across the previous 24 months or longer rather than only the most recently reported month. Alongside those base scores sit industry-specific versions for auto lending and credit cards, which run on a 250 to 900 scale rather than 300 to 850.

That version spread is the answer to the question this page exists for. A score shown free in a banking app or on a card statement is frequently a base FICO Score 8, or a VantageScore, which is a different model altogether from a different company. Mortgage lending has long run on older classic versions, one per bureau: FICO Score 2 at Experian, FICO Score 5 at Equifax, and FICO Score 4 at TransUnion, pulled together in what the industry calls a tri-merge. Those models were built on earlier data and are not calibrated to produce the same number as a FICO Score 8, so a gap of twenty or thirty points between your app and your loan file is ordinary rather than an error. Which versions a mortgage lender must use is set by the investors who buy the loan and by their regulator, and it changes, so the current requirement is worth confirming rather than assuming.

One convention inside the tri-merge decides which number actually prices the loan, and it is neither the highest nor the average. Fair Isaac describes mortgage lenders as selecting the middle score of the three. So the bureau holding your least favorable file does not sink the application on its own, and the bureau holding your best does not carry it. The practical consequence is that an error worth disputing before a mortgage application is one sitting on the middle file, and you cannot know which that is without looking at all three.

Congress anticipated this confusion. Under 15 USC 1681g(f)(1), a credit bureau that supplies you a score must include a statement that "the information and credit scoring model may be different than the credit score that may be used by the lender," along with the range of possible scores under the model used and up to four key factors that adversely affected it. The statute treats the score as a separate disclosure from your credit report, and 1681g(f)(8) lets the bureau charge a fair and reasonable fee for it, which is a useful reminder that the free annual report and the score are legally different things.

A lender orders a score from one or more bureaus. The bureau assembles your report, runs the licensed model version the lender has asked for, and returns a number plus the factors that held it back. Nothing about you is stored in the score itself, so it changes only when the underlying report changes, and it changes the moment that report does rather than on a monthly cycle. Because "amounts owed" is the second-heaviest category and the one you can move fastest, it is the usual lever.

A hypothetical example. Owen has three credit cards with limits of $4,000, $6,000, and $2,000, so $12,000 of available revolving credit, carrying balances of $1,800, $2,400, and $600, so $4,800 owed. His overall utilization is $4,800 ÷ $12,000 = 40%. He pays $2,200 against the balances, leaving $2,600, and utilization falls to $2,600 ÷ $12,000, or just under 22%. Nothing about his payment history or the age of his accounts has changed, but the category carrying 30% of the weight has moved substantially.

One mechanical detail defeats a lot of well-intentioned effort here. Card issuers typically report the balance as of the statement closing date, not the balance left after you pay the bill. Someone who charges heavily and pays in full every month can still have a high reported utilization, because the figure that reaches the bureau was captured before the payment. Paying before the statement closes, rather than before the due date, is what changes the number the model sees.

Pros

• One widely adopted standard means your record travels with you, so a lender you have never dealt with can price a loan for you in minutes.
• The inputs are limited to credit report data and are published, so the levers are knowable rather than a black box in the way the exact formula is.
• Free access to at least one FICO Score is now common through card issuers and banks.
• Payment history carries the most weight, which rewards the one behavior almost anyone can control.

Cons

• Many versions are in use at once, so the score you monitor may not be the score that prices your loan.
• A thin file or a long gap in borrowing can leave you unscoreable, which is not the same as having a low score but often has the same effect.
• It measures how you have handled credit, not whether you can afford a payment. Your income is not in a credit report, so it is not in the score.
• Errors in the underlying report flow straight into the number, and finding them is on you.
• Because the inputs are historical, most repair takes months, and the heaviest category is the slowest to improve.