Your credit score is a three-digit number that summarizes your credit history for lenders. But it’s not calculated arbitrarily — there’s a specific formula with defined components and weighted percentages. Understanding what goes into the calculation gives you a clear map for improving your score and maintaining it over time.
FICO vs. VantageScore: Two Major Models
There are two primary credit scoring models used in the United States: FICO and VantageScore. Both generate scores on a 300-to-850 scale, and both are used by lenders, though FICO remains dominant for mortgage lending and most major credit decisions.
FICO Score 8 (the most widely used version) breaks down score factors into five categories with defined weights. VantageScore uses similar factors but weights them differently. Most of the principles below apply to both models, with FICO percentages as the primary reference.
Payment History: 35% of Your FICO Score
This is the most heavily weighted factor. It answers one question: do you pay your accounts on time?
Every payment you make (or miss) on credit cards, loans, mortgages, and other lines of credit gets reported to the three major credit bureaus — Equifax, Experian, and TransUnion. On-time payments build positive history. Late payments create negative marks.
Late payments are categorized by severity:
- 30 days late: First reportable late payment; damages your score but less severely than later categories
- 60 days late: More significant negative impact
- 90 days late: Serious derogatory mark
- 120+ days late: Often precedes charge-off or collection
A single 30-day late payment can drop a previously excellent score (780+) by 80 to 110 points. The impact is temporary — it diminishes over time and disappears from your report after seven years — but the immediate effect is significant. Setting up autopay for at least the minimum payment on every account is the simplest way to protect this factor entirely.
Credit Utilization: 30% of Your FICO Score
Credit utilization is the percentage of your available revolving credit that you’re using. For credit cards, it’s calculated both per card and across all cards combined.
Formula: (total balances ÷ total credit limits) × 100 = utilization percentage
If your total credit limit across all cards is $10,000 and you currently owe $2,500, your utilization is 25%.
Lower utilization is consistently associated with higher scores. The commonly cited 30% threshold is a maximum, not a target. People with 800+ scores typically maintain utilization in the single digits — 5% to 10% or lower.
Key nuances:
- Utilization is typically measured on your statement date — the balance reported to bureaus is your statement balance, not your payment. You can have a balance on your card and still show 0% utilization if you pay before the statement closes.
- Per-card utilization matters as well as overall. A card at 85% utilization hurts your score even if your overall utilization is 20%.
- Utilization has no memory in most scoring models — it resets with each reporting cycle. Unlike late payments, high utilization doesn’t leave a lasting mark once reduced.
Length of Credit History: 15% of Your FICO Score
This factor evaluates the age of your credit accounts. Scoring models consider:
- The age of your oldest account
- The age of your newest account
- The average age of all accounts
Longer credit histories generally produce better scores, all else equal. This is why closing old credit card accounts is usually counterproductive — it removes the account’s age contribution from your average. Even a card you no longer use benefits your score while it remains open by maintaining your longest account age and keeping your overall average account age higher.
New credit applicants and young adults have naturally thin files and short histories. There’s no shortcut to aging an account — time is the only factor. Keeping your oldest accounts open and active is the key action here.
Credit Mix: 10% of Your FICO Score
Lenders want to see that you can manage different types of credit responsibly. Your credit mix includes:
- Revolving credit (credit cards, home equity lines of credit)
- Installment loans (auto loans, student loans, personal loans, mortgages)
Having at least one of each type in your history improves your score compared to only having one type. However, this factor only accounts for 10% of your score — don’t take out a loan you don’t need just to diversify your credit mix. The benefit doesn’t justify unnecessary debt.
New Credit: 10% of Your FICO Score
When you apply for new credit, the lender requests your credit report — a hard inquiry. Each hard inquiry temporarily reduces your score by a few points (typically 5 to 10), and the inquiry remains on your report for two years (though it only affects your score for about one year).
Opening several new accounts in a short time signals elevated risk to scoring models — it’s associated with financial distress in the data. Space out credit applications over time when possible.
One exception: rate shopping for mortgages, auto loans, or student loans. Scoring models typically recognize multiple inquiries for the same type of loan within a short window (14 to 45 days, depending on the model) as a single inquiry. Shopping multiple lenders for a mortgage won’t compound the inquiry penalty if you do it within that window.
What Doesn’t Affect Your Credit Score
Several factors that people often wonder about don’t appear in credit scoring calculations:
- Income and employment status
- Bank account balances
- Race, religion, national origin, sex, or age (prohibited by law)
- Soft inquiries (from your own credit checks, promotional offers, or employment background checks)
- Interest rates on your accounts
- Rent payments (usually — unless reported by a specialized service)
- Utility payments (usually — unless in collections)
The Practical Implications
To build and maintain a strong credit score, the hierarchy of actions by impact is clear:
- Never miss a payment — set up autopay for minimums on all accounts
- Keep credit card balances low relative to limits — ideally below 10% at reporting time
- Keep old accounts open — don’t close cards you’ve had for years
- Don’t apply for multiple new accounts at once — space applications out
- Maintain a mix of account types over time — let this develop naturally
The first two items account for 65% of your score. Getting those right, consistently, over 12 to 24 months produces a meaningfully improved credit profile regardless of where you’re starting from.
