Maya just got rejected for an apartment. The landlord told her her credit score was “too low” — but when she pulled it up on her phone, she couldn’t figure out why. She pays her bills. She doesn’t have a ton of debt. The number felt arbitrary.
It’s not arbitrary. Credit scores follow a specific formula, and once you understand it, you can work it intentionally. Here’s how the whole system actually works.
FICO vs. VantageScore: The Two Main Models
Two companies dominate credit scoring: FICO and VantageScore.
FICO — short for Fair Isaac Corporation — is what the vast majority of mortgage lenders, auto lenders, and credit card companies use when making decisions. When someone says “your credit score,” they almost always mean your FICO scoreFICO scoreThe most widely used credit scoring model, with scores ranging from 300 to 850.Full definition →.
VantageScore was created jointly by the three major credit bureaus as an alternative. It uses a similar range (300-850) and similar factors, but weights them slightly differently. VantageScore is common on free credit-monitoring apps. It’s a useful indicator, but don’t be surprised if the number you see on Credit Karma differs from the FICO score a lender pulls.
Both scores range from 300 to 850. Higher is better.
The Five Score Ranges
| Score Range | Category |
|---|---|
| 800–850 | Exceptional |
| 740–799 | Very Good |
| 670–739 | Good |
| 580–669 | Fair |
| 300–579 | Poor |
An “exceptional” score gets you the best interest rates available — lenders compete for you. A “good” score (670+) typically qualifies you for most loans at reasonable rates. Below 580, options shrink fast, and the interest rates on what’s available can be punishing.
The Five Factors (and What Each One Means)
FICO is built from five factors. Each carries a different weight in your score.
1. Payment History — 35%
This is the biggest single factor. It answers one question: do you pay on time?
Every on-time payment gets quietly noted. Every late payment gets noted too — and the damage is significant. A single 30-day late payment on an otherwise clean file can drop your score by 60 to 110 points. The exact impact depends on your starting score (higher scores fall further) and how recent the late payment is.
The practical lesson: if you can only do one thing right, pay every bill on time. Set up autopay for at least the minimum on every account so you never accidentally miss a due date.
2. Credit Utilization — 30%
Credit utilizationCredit utilizationThe percentage of your available credit you’re currently using — lower is better for your score.Full definition → is the percentage of your available credit that you’re currently using. If you have a credit card with a $5,000 limit and you’re carrying a $1,500 balance, your utilization on that card is 30%.
This is where most people have a critical misunderstanding. Utilization is calculated per card AND overall. You could have a total utilization of 15% across all your cards, but if one individual card is at 80%, that card is dragging your score down on its own.
For excellent credit, aim to keep each card — not just your total — under 10%. See our full breakdown at Credit Utilization: The Factor Most People Get Wrong.
3. Length of Credit History — 15%
This factor looks at how long your accounts have been open: the age of your oldest account, the age of your newest account, and the average age of all your accounts.
Older accounts help your score. This is why closing an old credit card — even one you rarely use — can hurt you. The account’s age is contributing to your average, and removing it lowers that average.
4. Credit Mix — 10%
Credit mix means having different types of credit accounts. The two main categories are:
- Revolving credit: credit cards, lines of credit — accounts where you borrow up to a limit and pay it back on a flexible schedule
- Installment loans: car loans, student loans, mortgages — accounts where you borrow a set amount and repay it in fixed monthly payments
Having both types suggests you can manage different kinds of debt responsibly. You don’t need to take out a loan just to improve your mix — but if you already have both types, maintaining them helps.
5. New Credit — 10%
Every time you formally apply for a credit card or loan, the lender performs a hard inquiry (also called a hard pull) — they check your credit file. Each hard inquiry can lower your score by a few points.
The impact is small and fades within about 12 months. If you’re rate-shopping for a mortgage or car loan, multiple inquiries within a 14-45 day window are typically treated as a single inquiry, so don’t let this stop you from comparing lenders.
The One Thing Most People Get Wrong About Utilization
Most people think they need to carry a small balance to “show activity” and build credit. This is wrong. Carrying a balance doesn’t help your score — it just costs you interest.
What matters is that you use the card and then pay it off. The credit bureau sees your balance at the time it’s reported (usually when your statement closes), not whether you paid it in full. Use the card, let the statement generate, then pay the full balance before the due date.
For more on the timing mechanics, see How to Check Your Credit Report for Free and How to Build Credit From Scratch.
A Quick Priority List
If you want to improve your score, work in this order:
- Get every payment on time (35% of score — the single most important thing)
- Bring utilization down below 30% on every card — below 10% if you’re chasing excellent credit
- Don’t close old accounts unless you have a compelling reason
- Don’t apply for multiple new cards at once
The formula isn’t a mystery. It’s a record of how reliably you borrow and repay. Build that record consistently, and the score follows.