Your credit score is a three-digit number that controls how much you pay for almost every major purchase in your adult life. Mortgage rates, car loans, insurance premiums, apartment approvals — all tied to this single number. Yet most people have no idea how it's actually calculated. This guide fixes that.
What Is a FICO Score?
FICO stands for Fair Isaac Corporation, the company that invented the modern credit scoring model in 1989. When a lender checks your credit, they're almost certainly pulling a FICO score — roughly 90% of top lenders use FICO for major credit decisions.
Your FICO score ranges from 300 to 850. Here's what each range means in practical terms:
| Score Range | Rating | What It Means |
|---|---|---|
| 800–850 | Exceptional | Best rates on everything, instant approvals |
| 740–799 | Very Good | Near-best rates, easy approvals |
| 670–739 | Good | Qualifies for most products at decent rates |
| 580–669 | Fair | Limited options, higher rates |
| 300–579 | Poor | Mostly denials or secured products only |
Target: 740+. This is the threshold where you unlock the best mortgage rates and premium credit card rewards. Going from 740 to 800 gets you minor improvements. Going from 620 to 740 can save you tens of thousands of dollars over a lifetime.
The 5 FICO Factors (With Exact Percentages)
FICO calculates your score using five weighted factors. Knowing these weights tells you exactly where to focus your energy.
1. Payment History — 35%
The single biggest factor. Did you pay every bill on time, every time?
Even one 30-day late payment can drop your score by 60–110 points. A 90-day late is worse. Collections, charge-offs, and bankruptcies are catastrophic. Conversely, a long streak of on-time payments is the most powerful credit-building tool available to you.
What counts: Credit cards, mortgages, auto loans, student loans, personal loans. Medical bills sent to collections also appear. Utility and rent payments don't typically appear unless reported through services like Experian Boost.
Key rule: Pay every bill on time, every time. Set up autopay for at least the minimum payment on every account. Never rely on memory.
2. Amounts Owed (Credit Utilization) — 30%
The second-biggest factor. This measures how much of your available revolving credit you're using.
Utilization formula: (Total balances ÷ Total credit limits) × 100
If you have $10,000 in total credit limits and $3,000 in balances, your utilization is 30%. FICO likes to see utilization below 30%, but the best scores require below 10%.
Critical insight: Utilization is calculated at the moment your lender reports your statement balance to the bureaus — not when you pay. Carrying a $0 balance isn't required; paying before the statement closes gets you low reported utilization.
If you want to maximize your score before a major application, pay down balances to under 10% of each card's limit two weeks before applying.
3. Length of Credit History — 15%
How long you've been using credit. FICO looks at:
- Age of your oldest account
- Age of your newest account
- Average age of all accounts
Older is better. This is why you should almost never close your oldest credit card — even if you never use it. A 15-year-old card with a $0 balance is helping your score by boosting your average account age and keeping your oldest account old.
Tip: If you're new to credit, time is your friend but you can't shortcut this. Focus on keeping old accounts open and not opening unnecessary new ones.
4. Credit Mix — 10%
FICO rewards you for successfully managing different types of credit:
- Revolving credit: Credit cards, lines of credit
- Installment loans: Mortgages, auto loans, student loans, personal loans
You don't need every type — but having both revolving and installment accounts helps. If you only have credit cards, adding a small credit-builder loan can improve your mix and your score.
5. New Credit (Hard Inquiries) — 10%
Every time you apply for new credit, the lender pulls a "hard inquiry" on your report. Each one can drop your score 5–10 points temporarily.
Exception for rate shopping: FICO treats multiple mortgage, auto, or student loan inquiries within a 14–45 day window as a single inquiry. So shop around freely for the best loan rate within that window.
For more on how inquiries affect your score, see our guide on hard vs. soft credit inquiries.
FICO 8 vs. FICO 9 vs. FICO 10: Which Version Matters?
This trips people up. There isn't one FICO score — there are dozens of versions.
FICO 8 (released 2009) remains the most widely used version across lenders. Most credit card approvals use FICO 8. It penalizes high utilization heavily and counts authorized user accounts.
FICO 9 (released 2014) made two borrower-friendly changes: paid collections no longer count against you, and medical collections are weighted less heavily. Not yet widely adopted.
FICO 10 / FICO 10T (released 2020) added "trended data" — looking at whether your balances are going up or down over time, not just the current snapshot. Rewarding people paying down debt, penalizing those accumulating it. Still in limited use.
Industry-specific scores: Mortgage lenders often use FICO 2, 4, and 5 (bureau-specific older versions). Auto lenders use FICO Auto Score. Credit card issuers use FICO Bankcard Score. These can vary 20–40 points from your standard FICO 8.
Practical takeaway: Focus on improving your underlying credit behaviors. Good habits improve all versions simultaneously. Check which version your lender uses before a major application.
What 50 or 100 Points Really Costs You (Real Dollar Examples)
Abstract score improvements feel meaningless until you see the money. Here's what score ranges mean for a $400,000 mortgage at 2026 rates (approximate):
| FICO Score | Mortgage Rate | Monthly Payment | 30-Year Total Interest |
|---|---|---|---|
| 760–850 | 6.5% | $2,528 | $510,080 |
| 700–759 | 6.75% | $2,594 | $533,840 |
| 680–699 | 6.9% | $2,633 | $547,880 |
| 660–679 | 7.1% | $2,685 | $566,600 |
| 640–659 | 7.5% | $2,797 | $606,920 |
| 620–639 | 7.9% | $2,912 | $648,320 |
Going from 639 to 760: Saves $384/month and $138,000 over 30 years. That's the cost of a score difference that most people could close within 12–18 months of deliberate credit management.
For auto loans, the impact is smaller but real. On a $35,000 car at 60 months, the difference between excellent credit (5.5%) and fair credit (13%) is about $135/month and $8,100 over the loan term.
Common Credit Score Myths — Debunked
Myth: Checking your own credit hurts your score. False. Checking your own credit is a "soft inquiry" and has zero impact on your score. Check it freely and often.
Myth: You need to carry a balance to build credit. False — and this one costs people real money. Carrying a balance means paying interest for no benefit. Pay your statement balance in full every month. The credit card reports your balance to the bureau before you pay it, so you still get credit for using the card.
Myth: Closing a credit card you don't use improves your score. Almost always false. Closing a card reduces your total available credit (raising utilization) and may reduce your average account age. Only close a card if it has an annual fee you can't justify.
Myth: Income affects your credit score. False. Income is not a factor in FICO scores. A millionaire with late payments has a worse credit score than a minimum-wage worker with perfect payment history.
Myth: Your credit score is the same everywhere. False. You have multiple scores across three bureaus (Equifax, Experian, TransUnion), multiple FICO versions, and VantageScore. They're all different. See our FICO vs. VantageScore guide for the full breakdown.
Myth: Paying off a collections account removes it from your report. False. A paid collection still stays on your report for seven years. It shows as "paid" which is marginally better. Your best move is negotiating a "pay for delete" agreement before paying, or disputing any inaccuracies. See our credit dispute guide for how to handle this.
How to Actually Move Your Score
Understanding the five factors gives you a clear action plan:
- Never miss a payment — autopay the minimum on everything, manually pay the full balance
- Keep utilization under 10% — pay down cards before statement close dates
- Keep old accounts open — don't close your oldest cards
- Don't apply for unnecessary credit — each hard inquiry costs points
- Add a credit mix if you only have one type — a credit-builder loan can help
If you're starting from scratch, see our build credit from scratch guide. If you have errors on your report dragging your score down, start with how to dispute credit report errors.
The math of credit is simple once you know the rules. A 740+ score is achievable for almost anyone with 12–24 months of consistent, informed behavior.
Part of the Complete Guide to Building Credit series.