How Credit Scores Actually Work (and the Myths That Don’t Move Them)

Your credit score is a three-digit prediction of one thing: how likely you are to pay back what you borrow, on time. The most widely used version, the FICO® Score, runs from 300 to 850. Lenders use it to decide whether to approve you and what interest rate to charge — which means a higher score is quite literally worth money, in lower rates on cards, car loans and mortgages.

As a rough guide: 670–739 is considered good, 740–799 very good, and 800+ exceptional. Below 580 is where approvals get hard and rates get painful.

The five factors, in order of weight

FICO publishes exactly what goes into its score. Your personal mix varies, but the proportions below are the official guide — and they tell you where effort pays off.

1. Payment history (35%) — the big one

Nothing moves your score like paying on time, and nothing sinks it like paying late. A single payment that goes 30 days late can knock a good score down hard, and the mark stays on your report for up to seven years (though its sting fades with time). The fix is boring and total: autopay at least the minimum on every account, so a forgotten due date can never become a late payment.

2. Amounts owed (30%) — watch your utilization

The key number here is credit utilization: your card balances divided by your credit limits. Owe $3,000 on a card with a $10,000 limit and you’re at 30% — the outer edge of what scoring models like to see. Under 30% is the common guidance; under 10% is better still. Utilization is calculated overall and per card, so one maxed-out card hurts even if the others are empty.

Two levers lower it: pay balances down (paying before the statement closing date means a lower balance gets reported), or ask for a higher limit and don’t spend into it. And note: with most widely used score versions, utilization is a snapshot — last month’s high balance doesn’t haunt you once you pay it down.

3. Length of history (15%) — time is an ingredient

You can’t rush this one, which is exactly why you shouldn’t sabotage it: closing your oldest card shortens your average account age and can also raise your utilization by removing its limit. If an old card has no annual fee, keeping it open — with a small recurring charge on autopay — quietly works in your favor.

4 & 5. New credit and mix (10% each) — the small stuff

Each credit application typically triggers a hard inquiry, which can shave a few points for a few months. Rate-shopping for a mortgage or auto loan is treated kindly — multiple inquiries within a short window (usually 14–45 days, depending on the model) count as one. Opening five store cards in a season, though, reads as risk. As for mix: it helps at the margins, but never take on a loan you don’t need just to “diversify” your file.

The myths that don’t move your score

• “Checking my own credit hurts it.” No. Checking your own score or report is a soft inquiry and has zero effect. Check freely — you’re entitled to free reports from all three bureaus at AnnualCreditReport.com.
• “Carrying a balance builds credit.” No — it builds interest charges. Your score cares that you pay on time and keep utilization low. Paying in full is both cheaper and just as good for the score.
• “My income is part of my score.” It isn’t. Lenders may ask about income on an application, but the score itself only reads your credit behavior.
• “Closing cards I don’t use helps.” Usually the opposite: it cuts your total limit (raising utilization) and can shorten your history. Fee-free old cards are worth keeping.
• “Debit cards and paying rent build credit.” Not by default. Debit activity isn’t reported, and rent and utilities only count if they’re reported through a specific service or program.
• “One bad month ruins me forever.” No. Scores recover as on-time payments stack up and utilization falls. The system rewards recent good behavior — start stacking it.

What to actually do, in order

1. Autopay everything — at least the minimum, everywhere, today. This defends the 35%.
2. Pull your free reports and dispute errors — a wrong late payment or someone else’s account is more common than you’d think, and removal is free.
3. Drive utilization under 30%, then under 10% — pay mid-cycle if you have to. This is the fastest lever you control.
4. Space out applications and keep old, fee-free cards open.
5. Then wait. History length and a clean streak compound quietly. Credit is a garden, not a slot machine.

High card balances are usually a sign the safety net is missing. Build the net first — here’s how to start an emergency fund with $500 — and the utilization problem starts solving itself.