Credit Utilisation, and Why the 30% Rule Is Folklore

Credit utilisation is the share of your available revolving credit that you are currently using. It is one of the heaviest factors in most credit scoring models, and it is also the subject of more confident misinformation than any other part of the system.

The calculation

Utilisation is your balance divided by your credit limit.

• $1,500 balance on a $5,000 limit is 30% utilisation
• $500 on a $5,000 limit is 10%

It is measured two ways at once: per card, and overall across every revolving account you hold. A single card run close to its limit can matter even when your total across all cards is modest.

Note what is excluded. Utilisation is a revolving-credit concept, so it applies to credit cards and lines of credit. Instalment debt like a mortgage, car loan or personal loan is not part of it, because those do not have a limit you can run back up.

The 30% figure is not a threshold

Here is the part worth being blunt about. The widely repeated advice to "keep utilisation under 30%" describes a rule that does not exist in any published scoring model.

The CFPB's guidance is to keep your balance low relative to your limit. It does not name a cutoff, because there is no cliff to name. Utilisation works as a gradient: lower is better, continuously. Going from 31% to 29% does not trip a switch. Going from 80% to 40% helps considerably, and going from 40% to 10% helps again.

Treat 30% as a rough waypoint that is better than 60% and worse than 10%, not a line you are safe behind.

It is a snapshot, not an average

This is the mechanically useful part, and most people do not know it.

Your issuer reports your balance to the credit bureaus periodically, typically around the statement closing date. That single figure becomes your reported utilisation until the next report. Scoring models see the snapshot, not your daily average and not your payment history within the cycle.

The consequence: someone who pays their statement in full every month can still show high utilisation. If you charge $2,000 on a $3,000 limit and pay it off in full after the statement closes, the bureaus were shown 67%. You pay no interest, you owe nothing, and your reported utilisation is poor anyway.

The fix is timing. Paying down the balance before the statement closing date, rather than before the due date, lowers the figure that gets reported. Those are two different dates, and only one of them affects utilisation.

What raises utilisation without you spending anything

• Closing a card. The balance stays and the limit vanishes, so the ratio rises. This is the main reason closing an unused card can hurt
• A limit reduction. Issuers sometimes cut limits on inactive accounts, which raises utilisation on any balance you carry
• A large purchase timed badly. Even a purchase you intend to pay off immediately can land inside the reporting snapshot

Conversely, a limit increase lowers utilisation instantly without you paying anything, though asking for one may involve a credit check.

What to actually do

• Pay before the statement closes, not just before the due date, if you want the reported figure low
• Keep old cards open, even unused ones, since the unused limit is helping you
• Spread balances rather than maxing one card, since per-card utilisation is visible
• Do not chase a specific percentage. Lower is better, and there is no number at which you have won

One caveat on all of this: utilisation is a large factor but not the largest. Payment history carries more weight in most models, and no amount of utilisation management offsets a missed payment. See what actually affects your credit score for how the factors compare.

Sources

• CFPB: What is a credit score?
• CFPB: Credit reports and scores
• CFPB: Credit cards

Current as of August 2026. Scoring models are proprietary and weightings are not published; the mechanics described here are drawn from CFPB consumer guidance.