FICO Score Explained: 5 Factors, 90% Rule
FICO is the credit score most major U.S. lenders reference before approving a mortgage, auto loan, or credit card. Understanding the five factors that build the 300–850 number — and which FICO version your lender pulls — helps you take targeted steps to improve it.
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What is a FICO score and why does it matter?
FICO — short for Fair Isaac Corporation — built the first commercial credit scoring model in 1989. Today, per FICO's own published data, FICO scores are used in over 90% of U.S. lending decisions, including most mortgage, auto, and credit card approvals. The model produces a 300–850 number from the data on your credit report. Higher number = lower predicted risk = lower APR offered.
The 5 FICO factors and exactly how much each one weighs
FICO's algorithm is proprietary, but the company publishes the relative weights of its five inputs. Memorize these — every score-improvement strategy maps to one of them.
| Factor | Weight | Fastest lever |
|---|---|---|
| Payment history | 35% | Autopay minimum on every account |
| Amounts owed (utilization) | 30% | Pay down balance before statement closes |
| Length of credit history | 15% | Never close oldest account |
| Credit mix | 10% | Add 1 installment loan if revolving-only |
| New credit / inquiries | 10% | Cap hard pulls at 1 per 6 months |
Payment history (35%) — the single biggest factor
One 30-day late payment can drop a 780 FICO by 80–110 points. The damage scales with how recent the late is — a late from 2 months ago hurts far more than one from 4 years ago. Lates fall off after 7 years. Set autopay on the minimum for every account; pay extra manually.
Amounts owed / utilization (30%) — the fastest factor to move
FICO calculates utilization per-card and aggregate. Under 10% is optimal. Under 30% is "fine". Above 50% materially drops your score. Trick: pay your card down to under 10% before the statement closes — only the reported balance is scored, not the daily average.
Length of credit history (15%)
FICO uses average age of accounts and age of oldest account. Closing your oldest card drops both. Authorized-user tradelines inherit the primary's age — adding a child to a 20-year-old Amex instantly gives them 20 years of history.
Credit mix (10%) and new credit (10%)
Revolving + installment performs better than revolving alone. One credit-builder loan or auto loan satisfies the mix factor. Hard inquiries cost ~5 points each and fall off after 12 months for FICO purposes (24 months for the report itself).
FICO 8 vs FICO 9 vs FICO 10T vs Mortgage FICO 2/4/5
"Your FICO" isn't one number — it's a family. The version your lender pulls determines what your score actually is.
| FICO version | Used by | Key behavior |
|---|---|---|
| FICO 8 | Most credit card issuers, personal loans | Standard 300–850, sensitive to utilization |
| FICO 9 | Some lenders, rent reporting | Ignores paid collections, weighs medical less |
| FICO 10T | Newer lenders, Fannie/Freddie 2025+ | Uses 24-month trended balance data |
| FICO Auto 8 | Auto lenders | 250–900 range, weights auto history more |
| FICO Bankcard 8 | Card issuers (credit-limit decisions) | 250–900, weights card behavior more |
| FICO 2/4/5 | Mortgage underwriting (current standard) | Older models, harsher on collections |
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- Daily monitoring & alerts
- Identity theft protection
- Score simulator & insights
- $1 for 15 days trial
- Cancel online anytime
- 3-Bureau credit reports & scores
- Daily monitoring & alerts
- Identity theft protection
- Score simulator & insights
- $1 for 15 days trial
- Cancel online anytime
FICO ranges — what each band unlocks
- 800–850 Exceptional — top-tier rates, jumbo mortgages, premium cards.
- 740–799 Very Good — best published rate on conventional mortgage and auto.
- 670–739 Good — where the U.S. median (717) sits; prime cards approve.
- 580–669 Fair — FHA mortgage possible, subprime cards.
- 300–579 Poor — secured products only.
Practical ways to raise your FICO score
- Drop reported utilization below 10% — pay before statement close. Score changes typically show in 30–45 days after the next statement is reported.
- Become an authorized user on a seasoned, low-utilization card. Inherits age + history.
- Dispute inaccurate negatives via the bureau direct (free, 30-day investigation window).
- Use Experian Boost or rent reporting to add positive history to thin files.
- Stop applying for new credit for 6 months before any major loan application.
We wrote an SSN-specific version of this guide with the key nuances and differences.
Read guideDo ITIN-only files get a FICO score?
Yes. FICO scores any file keyed to a valid taxpayer ID — SSN or ITIN — once the file meets the minimum scoring criteria: one tradeline open at least 6 months and updated in the last 6 months. Most ITIN holders reach FICO scorability 12–18 months after opening their first secured card. Until then, VantageScore 4.0 can score the file as early as month one.
Related credit-scoring guides
- Credit score range 300–850 tier by tier →
- VantageScore vs FICO compared →
- VantageScore 4.0 explained →
- SSN credit score range guide →
- ITIN credit score guide →
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FICO score frequently asked questions
What is a FICO score?
A FICO score is a 300–850 number generated by the Fair Isaac Corporation model from your credit file at Equifax, Experian, or TransUnion. 90% of top U.S. lenders pull a FICO before approving credit.
What are the 5 FICO factors and their weights?
Payment history 35%, amounts owed (utilization) 30%, length of credit history 15%, credit mix 10%, new credit / inquiries 10%. Payment history and utilization together drive 65% of your number.
What's the difference between FICO 8, FICO 9, and FICO 10T?
FICO 8 is the most-used version (cards, auto). FICO 9 ignores paid collections and weighs medical debt less. FICO 10T (released 2020) uses 24 months of trended balance data — carrying a balance hurts more even if you pay on time. Mortgage lenders still use FICO 2/4/5.
How fast can I raise my FICO score?
Paying down a maxed card to under 10% utilization can add 20–50 points in one statement cycle (30–45 days). Removing an inaccurate collection can add 50–100. New positive history takes 6+ months to materially move FICO 8.
Why do I have multiple different FICO scores?
FICO produces a different score per bureau (Equifax, Experian, TransUnion) and per industry version (Auto 8, Bankcard 8, Mortgage 2/4/5). Same file, different model. The lender chooses which one to pull.
Do I need an SSN to have a FICO score?
No. FICO scores files keyed to an ITIN as long as the file meets the scoring criteria: at least one tradeline open 6+ months and one update in the last 6 months. Most ITIN holders qualify within 12–18 months of opening their first secured card.
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