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Disclaimer: This calculator provides mathematical estimates based on the information you enter. It is intended for educational and informational purposes only and does not constitute professional advice. Consult a qualified professional before making financial, legal, medical or commercial decisions.

Clearing a credit card balance

Interest is charged on the balance, so paying a fixed amount each month clears the debt far faster than paying the minimum — which is designed to keep the balance alive.

What this calculator does

  • Works out how long a card balance takes to clear at a fixed monthly repayment.
  • Totals the interest paid over that period.
  • Makes the cost of a slower repayment visible.

How the calculation works

The APR is converted to a monthly rate and charged on the outstanding balance each month. Your payment covers that interest first, and only the remainder reduces the debt. That ordering is what makes credit card debt so persistent: at a high APR a large share of a small payment is absorbed by interest before any of it touches the balance. Raising the payment attacks the balance directly, and because next month's interest is charged on a smaller balance, the effect compounds in your favour — the time to clear falls much faster than the payment rises. The minimum payment is the mirror image of this. It is typically calculated as a small percentage of the balance, so it falls as the balance falls, stretching repayment over many years and maximising total interest. Paying a fixed amount rather than a shrinking percentage is the single most effective change available.

The rule

Each month: interest = balance × (APR ÷ 12), then balance = balance + interest − payment. Repeat until the balance reaches zero.

Step by step

  1. Convert the APR to a monthly interest rate.
  2. Charge that rate on the outstanding balance.
  3. Deduct the monthly payment, so the remainder reduces the balance.
  4. Repeat until the balance is cleared, counting the months.
  5. Total the interest charged along the way.

Worked example

A £3,000 balance on a card charging 24.9% APR, repaid at a fixed £150 a month.

What was entered

Inputs used in the worked example
Current card balance£3,000
Annual Percentage Rate (APR)24.9%
Monthly repayment£150

The arithmetic

  1. 24.9% APR is about 2.075% a month.
  2. The first month's interest is roughly £62, so only about £88 of the first £150 payment reduces the balance.
  3. As the balance falls the interest falls with it, so more of each payment goes to capital.
  4. The balance clears in 27 months.
  5. Total interest paid is £915.95 — about 31% of the original balance.
  6. Paying £200 a month instead would clear it appreciably sooner and cut the interest substantially, because every month saved is a month of interest avoided.

What the calculator returns

Results produced by the worked example
Months to clear27
Total interest paid£915.95

Key assumptions

  • The interest rate stays the same throughout.
  • The monthly payment is fixed and made on time every month.
  • No further spending is put on the card.

Limitations

  • Any new spending on the card resets the arithmetic, and this is the most common reason a repayment plan fails.
  • Real cards may apply different rates to purchases, cash advances and balance transfers, and payments are usually allocated to the highest-rate debt first.
  • Minimum payments, late fees and over-limit charges are not modelled.
  • A promotional 0% period would change the picture entirely until it ends.
  • If the debt is unmanageable, free and confidential debt advice is available from organisations such as MoneyHelper and Citizens Advice — that is a better first step than a calculator.

Common questions

Why does paying the minimum take so long?
Because the minimum is usually a percentage of the balance, so it shrinks as the balance shrinks. That stretches repayment over many years and maximises the interest charged. A fixed payment attacks the balance instead.
Why does a small increase in payment help so much?
Because the extra goes entirely to capital, and every month you cut from the schedule is a month of interest you never pay. The saving compounds, so raising the payment by a third can cut the time and the interest by considerably more than a third.
Should I clear the card before overpaying my mortgage?
Almost always, on the arithmetic alone. Card rates are typically several times mortgage rates, so a pound aimed at the card avoids far more interest than the same pound aimed at the mortgage.
What if I cannot afford the payment?
Free, confidential and impartial debt advice is available from MoneyHelper and Citizens Advice, and speaking to them early opens more options than waiting. Creditors are generally required to treat customers in financial difficulty fairly.

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Official sources

Every figure in this guide was checked against the sources below. Where a source could not confirm a figure, it is marked as requiring verification rather than presented as settled.