What Is a Credit Score? How Credit Scores Work

What a credit score actually is

A credit score is a three-digit number — almost always on a scale from 300 to 850 — that statistically predicts how likely you are to pay back what you borrow. It's built from the information in your credit reports: your loans and credit cards, your payment track record, how much you owe, and how long you've been using credit.

Lenders lean on that one number for two decisions: whether to approve you, and at what interest rate. A high score signals low risk, which earns you easier approvals and lower rates. A low score signals higher risk, so you'll face declines or steeper APRs. The same logic shows up beyond loans, too — landlords, insurers, and utility companies often check a credit-based score before they'll do business with you.

Importantly, your score isn't a permanent grade. It's recalculated every time your credit data changes, so the habits you build this month show up in the number within a billing cycle or two.

The five factors that determine a FICO score

FICO — the most widely used model — builds your score from five categories of information. The exact math is proprietary and the weights shift a little depending on your profile, but FICO publishes these approximate weightings:

Here's what each one really means:

• Payment history (~35%). The single biggest lever. Paying every bill by its due date builds the score; a missed payment, collection, or default can drop it sharply and linger for years. If you fix one thing, make it this.
• Amounts owed (~30%). This is mostly your credit utilization — the share of your available credit you're using. Carrying a $4,500 balance on a $5,000 limit (90% utilization) looks far riskier than carrying $500 (10%). Lower is better; staying under about 30% is a common rule of thumb.
• Length of credit history (~15%). Older accounts and a longer average age of credit work in your favor, because there's more track record to judge. This is why closing your oldest card can backfire.
• Credit mix (~10%). Handling a healthy blend — say, a credit card plus an installment loan like an auto or student loan — shows you can manage different kinds of debt. It's a minor factor; never take on debt just to diversify.
• New credit (~10%). Each application can trigger a hard inquiry and a small, temporary dip, and opening several accounts in a short window looks risky. Rate-shopping for a single loan in a focused window is usually treated as one inquiry, so it won't punish you for comparing offers.

FICO vs VantageScore

There isn't just one credit score. The two dominant models are FICO and VantageScore, and they both run on the same 300–850 range. They look at the same underlying credit-report data but weight and process it a little differently, so your FICO and VantageScore numbers usually land close to each other without matching exactly.

The practical distinction is who uses which. Most lenders — especially for mortgages and auto loans — pull a FICO score when they make a decision. Many free consumer tools, banking apps, and credit-monitoring dashboards, by contrast, display a VantageScore because it's freely available to them. That's the usual reason the number in your favorite app doesn't perfectly match what a lender quotes you. Neither is "wrong"; they're just different rulers measuring the same thing.

Credit score bands: what counts as good?

Scores are commonly grouped into bands. These are the widely cited FICO ranges (VantageScore uses similar, slightly different cutoffs):

The number to remember is 670. That's roughly the threshold where "Good" begins and you start qualifying for decent, mainstream rates rather than subprime terms. Everything above it just keeps improving your pricing and your options; the jump from Good to Very Good to Exceptional is the difference between a fine rate and the best rate on the board.

Why your score matters — in dollars

This is where an abstract number turns into real money. The exact same loan — same amount, same term — costs dramatically more with a lower score, because a weaker score means a higher APR, and a higher APR means more interest on every payment.

Take a $30,000, 60-month car loan. A borrower in the "Very Good" tier might land an APR around 7%, while a "Poor"-tier borrower on the same loan could be quoted something closer to 14% or more. That spread isn't a few dollars — over five years it can add up to thousands of dollars in extra interest for the identical car. The pattern repeats on mortgages, where a fraction of a percentage point spread across a six-figure balance over 30 years can mean tens of thousands of dollars.

Your credit score doesn't change the price of the car or the house. It changes the price of the money you borrow to buy it — and that's where the real cost hides.

The most convincing way to see this is to run the numbers yourself. Plug your loan amount and term into a calculator, then try it once at a "good"-tier APR and once at a "poor"-tier APR and watch the total interest move. The gap is almost always bigger than people expect — and it's the clearest argument for nudging your score up before you borrow. (Shopping for a fixed-rate personal loan instead? The same logic applies — try our personal loan calculator the same way.)

The bottom line

A credit score is just a 300–850 prediction of how reliably you repay debt, distilled from five factors with payment history and utilization doing most of the work. Cross 670 and you're in good shape for mainstream rates; keep climbing and the rates keep improving. Because the score sets your APR, it quietly determines the true cost of every loan you take — which makes building and protecting it one of the highest-return moves in personal finance.

Frequently asked questions