A FICO score is not a mystery; it is built from five broad categories of information, each carrying a published weight. Knowing those weights tells you where to spend your effort, because fixing a 35 percent factor moves your score far more than tinkering with a 10 percent one. The percentages below are the general weights FICO publishes for its base scores; the exact impact varies with your unique file.

Payment history (about 35 percent)

The single largest factor is whether you pay your bills on time, because past repayment behavior is the best predictor of future repayment. It counts on-time payments as well as negatives such as 30-, 60-, and 90-day late marks, collections, charge-offs, and bankruptcies. A recent missed payment hurts far more than an old one, and the more severe and recent the delinquency, the bigger the drop. This is why a single 30-day late can cost a high-scoring person many dozens of points.

Amounts owed and utilization (about 30 percent)

The second factor is how much you owe, and the most important piece is credit utilization, the share of your revolving limits you are using. It looks at utilization on each card and across all cards combined, so a single maxed-out card can hurt even if your overall ratio is low. Owing a lot relative to your limits suggests you may be overextended, so lower utilization generally means a higher score. Unlike payment history, this factor has no memory, so paying a balance down improves it as soon as the lower balance is reported.

Length of credit history (about 15 percent)

This factor rewards experience: the age of your oldest account, the average age of all accounts, and how long specific accounts have been open. A longer track record gives the model more data and generally supports a higher score. This is why opening several new accounts at once can pull down your average age, and why closing your oldest card can eventually hurt. Time is the only thing that builds this factor, so start early and be patient.

Credit mix (about 10 percent)

Credit mix looks at whether you handle different types of credit, such as revolving cards and installment loans like an auto loan or mortgage. Managing both revolving and installment accounts responsibly is viewed a little more favorably than handling only one type. Because it is a small factor, you should never take on a loan you do not need just to improve your mix. For most people, mix takes care of itself as their financial life naturally grows.

New credit (about 10 percent)

New credit tracks how many accounts you have opened recently and how many hard inquiries you have generated, because a burst of applications can signal financial stress. Opening several accounts in a short window lowers your average account age and stacks up inquiries, both of which can weigh on the score. A single new account or inquiry has only a minor, temporary effect. Spacing out applications keeps this factor from working against you.

Imagine you have a 760 score and one payment that slips past 30 days late. Because payment history is 35 percent and the mark is recent, your score could fall to the low 700s or worse. Meanwhile, paying a card from 80 percent down to 10 percent utilization could add a large number of points within a single billing cycle.

Key takeaways

  • Payment history (35 percent) and amounts owed (30 percent) together drive about two-thirds of a FICO score.
  • Utilization is the biggest movable lever and has no memory, so it responds fast to paying down balances.
  • Length of history (15 percent) only grows with time, so keep old accounts open.
  • Credit mix and new credit are 10 percent each, so never borrow just to game them.
  • Focus your energy on the heavy factors first.

Common mistakes

FAQ

Which factor should I fix first?

Start with payment history and utilization, since together they account for roughly 65 percent of the score and utilization responds quickly.

Do the percentages apply to everyone?

They are general weights. For someone with a thin or troubled file, the importance of each category can shift, but the ranking rarely changes much.