Three digits set the price on a mortgage, a car loan, an apartment application, and in most states your auto insurance premium. The gap is not small. On a $300,000 thirty-year mortgage, the spread between a 640 score and a 760 score can run past $150 a month in interest — roughly $54,000 over the life of the loan. Yet most people cannot name the five inputs that produce the number, let alone their weights.
The dominant scoring model, FICO, has published its recipe for years: payment history counts for 35 percent, amounts owed for 30 percent, length of credit history for 15 percent, new credit for 10 percent, and credit mix for the final 10 percent. VantageScore, the main competitor, uses similar ingredients with different labels and slightly different math. The percentages are approximations across the whole population — your personal file may lean harder on one factor — but the ranking holds. Here is what each input actually measures.
Payment history: 35 percent
The single biggest question a score tries to answer is blunt: does this person pay on time? A payment reported 30 days late can knock a strong score down by 60 to 100 points, and the damage is worst for people who had spotless files, because the model treats the first stumble as new information. Late payments stay on your credit report for seven years, though their weight fades steadily — a 30-day late from 2021 matters far less than one from last spring.
Two details trip people up. First, a payment is not reported late until it is a full 30 days past the due date; a payment five days late may trigger a fee from the card issuer, but it does not hit the bureaus. Second, severity tiers matter. A 30-day late is bad, a 90-day late is much worse, and a charge-off or an account sent to collections is worse still. If an old debt has already gone to a collector, the playbook changes entirely — what to do when a debt hits collections is its own topic.
Amounts owed: 30 percent
This factor is mostly about credit utilization — the share of your available revolving credit you are actually using. Someone carrying $4,500 in balances against $10,000 in total limits shows 45 percent utilization, which scoring models read as strain. Someone with the same $4,500 spread against $50,000 in limits shows 9 percent and reads as comfortable.
Utilization is measured per card and across all cards, and it is calculated from the balance your issuer reports on your statement date, not from whether you pay in full. That is why plenty of people who never pay a dime of interest still show high utilization. The folklore around the famous 30 percent threshold deserves its own correction — see what the 30 percent rule gets wrong — but the short version is that lower is simply better, and the effect reverses quickly once balances drop.
Length of credit history: 15 percent
Scoring models look at the age of your oldest account, the age of your newest, and the average age across the file. A ten-year-old card that sits in a drawer is quietly doing you a favor, which is why closing your oldest card is usually a mistake even when the issuer has annoyed you. The closed account keeps aging on your report for up to ten years, but its credit limit leaves the utilization math immediately.
There is no shortcut here, which is precisely why starting early matters. A 22-year-old who opens one card and pays it on time is building an asset no later hustle can replicate. For someone starting from an empty file, a deposit-backed card is the standard on-ramp — the mechanics are covered in how secured cards build a credit file from nothing.
New credit: 10 percent
Every application for credit that involves a lender pulling your file generates a hard inquiry. One inquiry typically costs a few points and fades within a year, dropping off the report entirely after two. A burst of applications in a short window looks like distress, which is the behavior the model is actually screening for.
The carve-out worth knowing: FICO treats multiple inquiries for the same loan type — mortgage, auto, student — within a shopping window (14 to 45 days depending on model version) as a single inquiry. Rate-shopping a mortgage across five lenders in two weeks is not punished. Opening five credit cards in two weeks is.
Credit mix: 10 percent
Models give modest credit for handling both revolving accounts (cards, lines of credit) and installment accounts (auto loans, student loans, mortgages). It is the least actionable factor: nobody should take out a loan they do not need to diversify a credit file, because the interest paid would dwarf the handful of points gained. Treat mix as a byproduct of a normal financial life, not a target.
What is not in the score
The list of exclusions surprises people. Your income is not in your credit score. Neither is your employer, your rent (unless a service reports it), your bank balances, your age, your marital status, or your ZIP code. Federal law bars the use of race, religion, and national origin. A surgeon earning $600,000 with maxed-out cards can score worse than a barista with two years of clean payments. The score measures how you have handled borrowed money — nothing else.
Checking your own score is also harmless. Pulling your own report or using a score-tracking app is a soft inquiry, invisible to the model. I have met people who went years without looking at their own credit file out of fear of damaging it, which is a little like refusing to step on a scale in case it adds weight.
Where the data comes from — and why you should audit it
Scores are computed from the contents of your credit reports at Equifax, Experian, and TransUnion. Garbage in, garbage out: a report error — a paid account showing a balance, someone else's collection, a late payment you never made — flows straight into the number. Federal law entitles you to free reports from all three bureaus through AnnualCreditReport.com, now available weekly rather than the old once-a-year allotment. The Consumer Financial Protection Bureau publishes plain-language guidance on how credit scores work if you want the regulator's own framing.
If you find something wrong, you have a formal dispute right with real teeth — the process and the paper trail are laid out in how to dispute a credit report error and win.
A realistic order of operations
- Automate minimum payments on everything. This protects the 35 percent factor from a missed due date, which is the single most expensive mistake available.
- Push utilization down. Pay balances before the statement closes, or ask for limit increases you will not spend. This is the fastest-moving lever in the entire system.
- Leave old accounts open unless an annual fee forces the issue.
- Space out applications and consolidate rate-shopping into a tight window.
- Ignore credit mix. It will take care of itself.
Your next step costs nothing: pull all three of your reports this week and read every account line. Most people find the exercise boring, which is the best possible outcome. A few find the error that has been quietly costing them money for years.
