How Credit Scores Work: The 5 Factors That Decide Your Score

Your credit score is a three-digit number that quietly shapes some of the biggest prices in your life: the interest rate on your mortgage, the deposit your landlord demands, the premium on your car insurance in many states, and whether a lender approves you at all. Yet most people have only a vague idea of how the number is actually calculated.

The formula is not a secret. FICO, the company behind the most widely used scoring models, publishes the five ingredients and roughly how much each one counts. Once you understand those weights, most credit advice stops sounding like folklore and starts looking like arithmetic: pay on time, keep balances low relative to limits, let accounts age, and don’t apply for everything in sight.

This guide walks through each of the five factors, shows what a weak score costs you in real dollars, and lays out the moves that actually raise a score — ranked by how much they matter.

What a Credit Score Actually Measures

A credit score is a prediction. It estimates the likelihood that you will fall at least 90 days behind on a payment within the next 24 months, based entirely on the information in your credit report — the file of your borrowing history maintained by the three major bureaus: Equifax, Experian, and TransUnion.

That distinction matters. The score does not know your salary, your savings balance, your rent (unless it’s reported), or your net worth. A surgeon earning $400,000 a year can have a terrible score; a barista earning $28,000 can have an 800. The score only sees how you have handled credit that appears on your report.

Scores run from 300 to 850 on the standard scale. Here is how lenders generally read the ranges:

• 300–579 (Poor): Approvals are difficult; expect deposits, cosigner requirements, or subprime loan terms.
• 580–669 (Fair): You can get credit, but at noticeably higher rates.
• 670–739 (Good): Approvals come easier and pricing improves.
• 740–799 (Very Good): You qualify for most lenders’ best or near-best rates.
• 800–850 (Exceptional): Pricing is essentially maxed out; the extra points are bragging rights.

FICO vs. VantageScore

You have more than one score. FICO scores are used in the vast majority of lending decisions, especially mortgages. VantageScore, created jointly by the three bureaus, is common on free score-tracking apps. Both use the same underlying report data and reward the same behaviors, but the exact numbers can differ by 20 points or more. Don’t panic over the gap — track the trend, not the model. The Consumer Financial Protection Bureau has plain-English explainers on how the models differ if you want to go deeper.

The 5 Factors and How Much Each One Counts

FICO weights the ingredients of your score roughly like this:

The percentages are approximate — the model adjusts for people with thin files — but the ranking is the point. Payment history and amounts owed together drive about 65% of your score. Get those two right and the rest largely takes care of itself.

1. Payment History (35%)

Nothing matters more than paying at least the minimum on time, every time. One payment reported 30 days late can knock 60–100 points off a strong score, and it stays on your report for up to seven years, although its weight fades as it ages.

Key details people miss:

• Lenders can only report you late once you’re a full 30 days past the due date. A payment that’s five days late may trigger a late fee but won’t hit your report.
• Severity escalates: 30, 60, and 90-day lates each hurt more, and charge-offs, collections, and bankruptcies hurt most of all.
• Autopay for at least the minimum payment is the single cheapest insurance policy in personal finance.

2. Amounts Owed (30%)

This factor is mostly about credit utilization — your card balances divided by your credit limits. If you carry a $2,500 balance across cards with $10,000 in total limits, your utilization is 25%. Scoring models read high utilization as financial stress, even if you pay in full every month, because most issuers report the balance on your statement date.

Utilization has no memory: the moment a lower balance is reported, the points come back. That makes it the fastest lever you can pull. The mechanics — including why the famous 30% rule is more myth than target — get a full treatment in our guide to credit utilization and what really matters.

3. Length of Credit History (15%)

This looks at the age of your oldest account, the average age of all accounts, and how long it’s been since you used them. There’s no shortcut here except time — which is exactly why keeping your oldest no-fee card open, even if you rarely use it, quietly helps your score for decades.

4. Credit Mix (10%)

Scores modestly favor people who have handled both revolving credit (credit cards) and installment credit (auto loans, student loans, mortgages). Never take out a loan just to improve mix — 10% of your score is not worth paying interest for. This factor mostly rewards a mix you acquire naturally over a lifetime.

5. New Credit (10%)

Each application for credit triggers a hard inquiry, which typically costs 5–10 points and stops affecting your score after 12 months. Opening several accounts in a short window is a stronger negative signal than one inquiry. Rate-shopping for a mortgage, auto loan, or student loan gets special treatment: multiple inquiries within a 14–45 day window count as one.

What Your Score Costs You in Real Dollars

The clearest way to see why any of this matters is a mortgage. Suppose you’re borrowing $300,000 on a 30-year fixed loan, and your score determines whether you’re quoted 6.5% or 7.5%:

That one-point rate difference costs about $202 every month and roughly $72,600 over the life of the loan — the price of a nice car, paid entirely because of a number. You can run your own scenarios with our loan payment calculator, and if a home purchase is on your horizon, start with our first-time buyer’s guide to mortgages.

The same logic applies at smaller scale to auto loans, personal loans, and credit card APRs. Weak credit doesn’t just limit options; it adds a percentage-point tax to almost everything you finance.

How to Check Your Reports and Scores for Free

Your score is calculated from your report, so start with the report itself:

1. Pull your reports from all three bureaus at AnnualCreditReport.com, the official source authorized by federal law — currently you can check each bureau weekly for free.
2. Read every account. Confirm the balances, limits, and payment history are yours and accurate.
3. Dispute errors directly with the bureau reporting them. The CFPB publishes step-by-step dispute instructions at consumerfinance.gov, and bureaus generally must investigate within 30 days.
4. For ongoing score tracking, use the free score access most card issuers and banks now provide.

Errors are not rare. A significant share of consumers find at least one mistake on a report, and a wrong late payment or an account that isn’t yours can be worth a fast 50-plus points once corrected.

Seven Moves That Raise Your Score, Ranked

In rough order of impact per unit of effort:

1. Automate minimum payments on every account, then pay the rest manually. This makes the 35% factor untouchable.
2. Pay card balances before the statement closes so a low number gets reported. This attacks the 30% factor immediately.
3. Pay down revolving debt. If you’re carrying balances month to month, a payoff plan helps your score and your wallet — see our realistic plan for paying off credit card debt.
4. Request credit limit increases on cards you already have (ask whether it’s a soft pull). A higher limit lowers utilization with zero behavior change.
5. Keep old no-fee accounts open to protect your average account age.
6. Dispute report errors — the highest-value paperwork in personal finance.
7. Add new accounts sparingly and strategically. If you’re starting from nothing, a secured credit card is the standard on-ramp.

Common Credit Score Myths

A few persistent pieces of folklore deserve a direct debunking:

• “Carrying a balance helps your score.” False, and expensive. Paying in full builds identical payment history and costs $0 in interest. The Federal Reserve reports average card APRs above 20% in recent years — you can see the data yourself in the Federal Reserve’s consumer credit statistics. There is no scoring bonus that justifies paying that.
• “Checking my score hurts it.” Soft inquiries — checking your own score, prequalification offers, employer checks — never affect your score.
• “Closing a card cleans up my credit.” Closing a card usually hurts in the short run, because you lose its credit limit and utilization rises.
• “You only have one score.” You have dozens across models and bureaus. Lenders pick which one they use.
• “Income affects your score.” It affects approvals (lenders ask), but it appears nowhere in the scoring formula.

How Fast Can Your Score Change?

Faster than most people expect, in one direction — utilization changes register as soon as new balances are reported, so paying down maxed-out cards can add serious points within one or two billing cycles.

Slower in the other. Recovering from a missed payment or collection is a matter of stacking clean months on top of the blemish. As a rule of thumb:

• 1–2 months: utilization improvements, error corrections.
• 3–6 months: building a first score from a new account, recovering from a batch of hard inquiries.
• 12–24 months: meaningful recovery after a late payment, as newer history dilutes it.
• 7 years: most negative marks fall off entirely (10 for some bankruptcies).

If you’re starting from scratch, expect roughly six months of reported history before FICO can generate a score at all — and choose that first account carefully using our guide to picking your first credit card.

Who Checks Your Score — and Which Score They See

Different decision-makers pull different scores from different bureaus, which explains why the number you see in an app rarely matches the number a lender quotes.

• Mortgage lenders traditionally pull a “tri-merge” report — one score from each bureau, using older FICO models specific to mortgage lending — and price your loan off the middle of the three. If your Experian, Equifax, and TransUnion scores are 728, 741, and 756, you’re a 741 for mortgage purposes. This is why cleaning up errors at all three bureaus matters before a home purchase.
• Auto lenders often use FICO Auto Scores, industry-specific models that weight your history with vehicle loans more heavily. Your auto score can run noticeably higher or lower than your standard score.
• Card issuers typically use FICO Bankcard models or standard FICO 8, pulled from whichever single bureau they contract with — which can vary even between applications to the same bank.
• Landlords usually run a credit and background screening product rather than a pure score, weighing collections, evictions, and payment history.
• Insurers in most states use credit-based insurance scores — yet another model — to help set premiums on auto and homeowners policies. A handful of states ban or restrict the practice.
• Employers never see your score at all. With your written consent, some see a modified version of your report for certain roles, but no score is attached.
• Utility and phone companies may check your credit to decide whether you owe a security deposit — one of the quieter ways a thin or damaged file costs cash up front.

The practical takeaway is twofold. First, don’t fixate on any single number; the free score you monitor is a barometer, not the exact figure every lender will use. Second, the behaviors underneath are identical across every model — pay on time, keep utilization low, age gracefully — so improving the fundamentals lifts all of your scores at once, whichever one gets pulled.

It also means timing matters. Because lenders pull fresh data at application, the version of your file that exists that week is the one that gets priced. Planning a major application a few months out gives you time to pay down reported balances and let recent inquiries age — cheap moves with real pricing consequences.

The Bottom Line

A credit score is not a judgment of your character or your income. It’s a narrow, mechanical prediction built from five inputs — and two of them, payment history and utilization, control about two-thirds of the result. Automate your payments so you never miss one, keep reported balances low relative to limits, and you are already doing the majority of what an 800-score household does.

The rest is patience: let accounts age, apply for new credit deliberately rather than impulsively, and check your reports for errors once or twice a year. None of it requires wealth. It requires consistency, which is exactly what the model is designed to detect.

Treat the score as a byproduct of good habits rather than a goal to chase, and the dollar savings — on mortgages, car loans, insurance, and deposits — will follow on their own.