Credit scores feel like a black box — a number that affects major financial decisions but seems to change unpredictably. The calculation isn’t secret, though. Understanding exactly what goes into your score explains why it changes when it does and what actions actually move the needle.
The Two Main Scoring Systems
Most lenders use either FICO scores or VantageScores, and both range from 300 to 850. FICO is the older and more widely used model — the majority of lending decisions, particularly for mortgages and auto loans, rely on FICO scores. VantageScore is used by some lenders and is the score most often shown in free consumer monitoring apps.
The factors that drive both scores are similar, but the weights differ. FICO’s factor weights are publicly documented. VantageScore’s exact weighting is less transparent but the general categories are the same.
The Five FICO Score Factors
1. Payment History (35%)
This is the dominant factor. Every on-time payment adds positive history; every late payment creates a negative mark. The severity of impact varies:
- 30-day late: less severe than 60 or 90-day lates
- 90+ day late: significantly damaging and stays on your report for 7 years
- Collections and charge-offs: major negative marks
- Bankruptcy: the most severe, stays 7–10 years depending on type
Recency matters too. A late payment from six years ago has less impact than one from last year. Recent, consistent on-time payments can recover from older negative marks over time.
2. Credit Utilization (30%)
Utilization is your total revolving credit balances divided by your total revolving credit limits. If you have two credit cards with a combined limit of $10,000 and you’re carrying $3,000 in balances, your utilization is 30%.
Lower utilization generally means higher scores. The commonly cited threshold is 30%, but the highest-scoring consumers typically use well under 10% of their available credit. Utilization is calculated on each individual card as well as in aggregate — one maxed-out card can hurt even if your overall utilization is low.
Importantly, utilization is a snapshot, not a history. It reflects your balance at the time your creditor reports to the bureau (usually the statement closing date). Paying down balances raises your score relatively quickly compared to other factors.
3. Length of Credit History (15%)
This factor looks at the age of your oldest account, the age of your newest account, and the average age of all accounts. Longer history is better. This is why closing old credit cards — especially your oldest one — can lower your score, even if you’re not using the card. The account closure removes that history from the average age calculation.
Older negative items affect this factor too, but their score impact diminishes as they age.
4. Credit Mix (10%)
Having different types of credit — revolving credit (credit cards, lines of credit) and installment loans (auto loans, mortgages, student loans, personal loans) — contributes positively. The model rewards diversity because it demonstrates you can handle different types of borrowing obligations.
This doesn’t mean you should take out loans to improve your mix. The 10% weight means adding an unnecessary loan for scoring purposes rarely makes financial sense.
5. New Credit (10%)
Each new credit application triggers a hard inquiry, which typically lowers your score by a few points temporarily. New accounts also lower the average age of your accounts. Multiple applications in a short window look like financial distress to scoring models.
The impact of a single hard inquiry is modest and typically fades within 12 months. The impact of five inquiries in three months is more significant. Rate shopping for a mortgage or auto loan within a defined window (14–45 days depending on the scoring model) is treated as a single inquiry.
What FICO Doesn’t Include
A few things commonly assumed to affect credit scores actually don’t:
- Your income — not reported to credit bureaus
- Your employment history — not in the score calculation
- Checking and savings account balances
- Rent and utility payments (unless through a reporting service)
- Checking your own credit score (soft pulls have no score impact)
The Different FICO Score Versions
FICO has released multiple versions (FICO 8, FICO 9, FICO 10, FICO 10T), and different lenders use different versions. Auto lenders often use industry-specific FICO Auto Scores. Mortgage lenders typically still use older FICO versions (FICO 2, 4, or 5) as required by government-sponsored entities.
This means the score you see in a consumer app (often FICO 8) may not be identical to what a specific lender sees. The scores typically move in the same direction for the same reasons, but the exact number can vary. The free score is still useful for tracking your relative position; just don’t be surprised if the number a lender cites differs slightly.
What Actually Moves Your Score
Given the factor weights, the highest-leverage actions are:
- Never miss a payment — set up autopay for at least the minimum on every account
- Pay down revolving balances to below 30% (ideally below 10%) of limits
- Don’t close old accounts you’re not using (unless they carry fees you can’t justify)
- Limit new credit applications to those you actually need
Score improvement from these actions isn’t instant, but it’s reliable. Consistent behavior over 12–24 months produces meaningful improvements for most people starting from a lower score.
