How Credit Scores Are Actually Calculated
Five factors, with published weightings, explain almost everything about a credit score. Most of the advice circulating about them is wrong, and some of it actively lowers your score.
A $5,000 credit card balance at 22% costs $8,680 in interest if you pay $100 a month. Raise it to $150 and the same balance costs $2,800 and clears seven years sooner. Here is the arithmetic.
A credit card minimum payment is typically the greater of a small fixed sum (often around $25) and a percentage of the balance (commonly 1–3%, sometimes plus that month's interest and fees). It is set by the issuer to keep the account performing. It is not designed to get you out of debt, and it does not.
The arithmetic below is worth doing once, carefully, because most people underestimate the result by a wide margin.
Take a $5,000 balance at 22% APR, with no further spending on the card.
| Monthly payment | Time to clear | Total interest | Total paid |
|---|---|---|---|
| $100 | 11 years 5 months | $8,680 | $13,680 |
| $150 | 4 years 4 months | $2,800 | $7,800 |
| $200 | 2 years 10 months | $1,750 | $6,750 |
| $300 | 1 year 9 months | $1,020 | $6,020 |
Read the first two rows again. Adding $50 a month — $600 a year — cuts the interest bill from $8,680 to $2,800 and the timeline from eleven years to four. That extra $50 saves $5,880, a return on the money of roughly ten to one.
The reason is visible in the first month. At 22%, a $5,000 balance accrues about $91.67 of interest. Pay $100 and $8.33 reduces the balance. Pay $150 and $58.33 does. The second payment is 50% larger and reduces the debt seven times faster, because interest is taken first and only the remainder touches the principal.
If your minimum is a percentage of the balance, it falls as the balance falls. A 2% minimum on $5,000 is $100; on $2,000 it is $40; on $800 it is the $25 floor. The payment shrinks in step with your progress, which is exactly what stretches the tail of the debt across a decade. Paying a fixed amount rather than "the minimum" removes this effect entirely and costs nothing extra.
Rate matters enormously, which is why moving a balance to a cheaper product is often worth more than any amount of budgeting discipline.
| APR | Time to clear | Total interest |
|---|---|---|
| 0% (promotional balance transfer) | 2 years 10 months | $0 |
| 9% (personal loan) | 3 years 3 months | $775 |
| 15% | 3 years 8 months | $1,510 |
| 22% (typical card) | 4 years 4 months | $2,800 |
| 29% (store card) | 5 years 9 months | $5,290 |
Identical balance, identical payment. The gap between the top and bottom rows is $5,290 and nearly three years — decided entirely by the rate on the account.
No payoff plan survives continued spending on the same card. Remove it from your wallet, delete it from browsers and app stores, and switch recurring payments to a debit card. If the card was covering shortfalls at the end of the month, that is a budgeting problem the payoff plan cannot fix on its own — see how to build a budget.
Choose a number above the current minimum and set it as a standing payment that does not fall as the balance does. Even a modest fixed amount transforms the timeline for the reason described above.
The table above shows what an extra $50 is worth. Most households can find it in an afternoon of fixed-cost cutting — an insurance renegotiation, two unused subscriptions, a mobile contract — without changing anything they would notice day to day.
In the US, the CARD Act of 2009 requires card statements to show how long the balance would take to clear at the minimum payment, and what a payment sufficient to clear it in three years would be. Several other countries have adopted similar requirements.
It is the most useful box on the statement and almost nobody reads it. Find it this month. The number in it is frequently the thing that finally makes people change the standing order.
If minimum payments are already at the limit of what you can afford, the guidance above does not apply, and the priority shifts from optimisation to getting help early.
Paying the minimum on time keeps your payment history clean, which is the largest scoring factor. But a high balance relative to your limit damages the second-largest factor, credit utilisation, which counts for about 30% of a FICO score. So minimum payments protect one part of your score while gradually harming another. See how credit scores work.
Build a small buffer of around $1,000 first, then attack the card, then complete your full emergency fund. A savings account paying 4% while a card charges 22% loses you 18% a year on every dollar held in both places — but having no cash at all means the next unexpected bill goes straight back on the card. The order of operations sets out the full sequence.