How Credit Scores Work (and How to Improve Yours)

A credit score is a three-digit estimate of how likely you are to repay borrowed money. It sets the interest rate you are offered, whether you are approved at all, and sometimes a utility deposit or an apartment application. It is not a measure of wealth or of character, and it is built from a short list of inputs you can act on directly.

What the number means

The two dominant models, FICO and VantageScore, both run from 300 to 850. The bands are approximate and lenders set their own cutoffs, but broadly: 800 and above is exceptional, 740–799 very good, 670–739 good, 580–669 fair, and below 580 poor.

You do not have one score. Each bureau — Equifax, Experian and TransUnion — holds its own file, and lenders pull different model versions, including industry-specific ones for cars and mortgages. A 20-point spread between bureaus is normal and rarely worth investigating. A 100-point spread usually means something is on one report and not the others, which is worth investigating immediately.

The five factors that build it

• Payment history (~35%). Whether you pay on time. Nothing else comes close, and a single payment reported 30 days late can cost a good score dozens of points.
• Amounts owed, mostly utilization (~30%). How much of your available revolving credit you are using. Under 30% is the common advice; under 10% is where the best scores sit.
• Length of credit history (~15%). The age of your oldest account and the average age of all of them. This is why closing an old card can hurt.
• Credit mix (~10%). Holding both revolving credit (cards) and instalment credit (loans). Minor, and never worth taking on a loan you do not need.
• New credit (~10%). Recent applications and hard inquiries, which cost a few points each and fade within a year.

The percentages are FICO's published weightings for a typical file, not a formula applied identically to everyone. A thin file with two accounts is scored differently from a thirty-year file with fifteen.

What the score is worth in dollars

The gap between a fair score and a very good one is not abstract. On a $350,000 30-year mortgage, the difference between 6.5% and 7.0% — a spread a hundred points of score can easily explain — is about $116 a month, and roughly $41,900 across the life of the loan.

Car loans compress the same effect into five years. On a $28,000 loan, moving from 12.9% to 6.9% saves about $4,950 in interest. That is the return on repairing a score before shopping, which is why the repair should come first when the purchase can wait.

Utilization is the fastest lever

Payment history matters most, but it is slow to change: a clean month adds little, and a missed one costs a lot. Utilization is the opposite. It is recalculated every time your balances are reported, usually monthly, and carries no memory — last year's maxed-out card does not weigh on today's ratio once the balance is gone.

Two details decide how quickly that helps you:

• It is measured per card and across all cards together. One card at 95% can hurt even when your overall ratio looks healthy.
• Issuers usually report the balance on your statement date, not after your due date. Paying in full every month can still report high utilization if you pay after the statement closes — so paying down before the statement date is what the score actually sees.

Raising a limit works the same way as paying a balance down, since the ratio falls either way, provided the new room goes unused. A limit increase is often a soft pull; ask before assuming it costs you an inquiry.

What is not in your score

• Your income, savings or net worth. Lenders weigh these separately, which is why a high earner can have a poor score.
• Checking your own score or report. That is a soft inquiry and is invisible to scoring models.
• Carrying a balance month to month. This does not build credit; it builds interest. Paying in full scores the same and costs nothing.
• Debit card use, or paying rent and utilities — unless you enrol in a service that reports them.

Rate shopping is also less damaging than feared: multiple mortgage or auto inquiries inside a short window, typically 14 to 45 days depending on the model, are counted as a single inquiry. Shopping several lenders in the same fortnight is the intended behaviour, not a penalty.

How long damage lasts

Negative marks age off on fixed schedules. Most, including late payments, collections and charge-offs, drop off seven years after the original delinquency. A Chapter 7 bankruptcy stays for ten. Hard inquiries stop affecting the score after twelve months and disappear from the report after two years.

The practical consequence is that the damage shrinks long before it vanishes. A late payment from four years ago, followed by four clean years, weighs far less than its presence on the report suggests.

Rebuilding, in order

• Get current, then stay current. Nothing else works while payments are being missed. Automate the minimums.
• Pull all three reports and dispute errors. Mistakes are common, and an account that is not yours is the fastest hundred points anyone ever gains.
• Cut utilization on the highest-percentage card first — this is the fastest legitimate move available.
• Leave old accounts open. Closing one shortens your history and removes its limit from the ratio, damaging two factors at once.
• Stop applying. Every application is a small cost with no benefit while you are rebuilding.

Be sceptical of anyone selling faster results. Credit repair firms can only dispute what you can dispute yourself for free, and accurate negative information cannot be removed by anyone at any price.

Where to check

Federal law entitles you to free reports from all three bureaus at AnnualCreditReport.com, the only site authorised to provide them. Most banks and card issuers now show a score for free as well — usually a VantageScore, which will not exactly match the FICO score a mortgage lender pulls, but tracks the same direction.

Run your own number

See exactly where your ratio sits, per card and overall, in the credit utilization calculator. Work out how fast the balances behind it can go in the credit card payoff calculator, check the other ratio lenders judge you on with the debt-to-income calculator, and price what a better score is worth on your next loan in the mortgage calculator.