Credit card payoff calculator

Enter a balance, a rate and what you can pay each month, and this works out how long the card takes to clear and what the interest costs.

Credit card rates in Australia commonly run around 20%, which is roughly three times a mortgage rate. At that level the interest cost of taking an extra year is substantial, and this makes the size of it explicit.

What to enter

Monthly repayment
A fixed amount you pay each month — not the card’s minimum, which falls as the balance does and stretches the payoff enormously.

Reading the result

The total interest against the balance is the figure to sit with. On a high rate paid slowly, the interest can approach the balance itself.

Raise the repayment by a modest amount and re-run it. The reduction in both time and interest is disproportionate, because at high rates most of a small payment is being consumed by interest before it touches the balance.

If the calculator reports that the balance never clears, the repayment is below the interest charged each month. That situation does not improve on its own.

Worked examples

Every figure below is computed by the same calculator on this page, from the inputs described. Nothing here is typed in by hand, so an example cannot disagree with the tool.

$8,000 at 20.99%, paying $300 a month

Months to clear the balance: 37
Card balance: $8,000
Monthly repayment: $300

Note the total interest. At this rate and payment a large fraction of what you pay goes to the lender rather than the balance.

The same balance at $500 a month

Months to clear the balance: 19
Card balance: $8,000
Monthly repayment: $500

Two-thirds more per month, and both the term and the interest fall by much more than two-thirds. High rates make extra payments unusually valuable.

How it is worked out

Interest is added monthly at the annual rate divided by twelve, then the repayment is subtracted, and the months are counted until the balance reaches zero.

If the first month’s interest is not less than the repayment, the balance cannot fall and the calculator says so rather than returning an arbitrary number.

How every calculator on this site is built

What it assumes

No new spending on the card
The balance only goes down. Continuing to use the card while paying it off changes the answer completely and is the most common reason a real payoff takes longer than a calculated one.
A fixed repayment
Card minimums are typically a percentage of the balance with a floor, so they shrink as you pay down and dramatically extend the term. Paying a fixed amount is the better strategy and the one modelled.
No interest-free period
Interest-free days generally do not apply once a balance is carried. The model charges interest from the first month, which reflects a card in that state.

Where it stops being right

Balance transfers are not modelled
A 0% balance transfer changes the arithmetic entirely for its promotional period. Compare the payoff at 0% over the promotional term against this, and check what the rate reverts to.
Fees are excluded
Annual card fees, cash advance fees and late fees are not included and are charged on top.

How long to repay calculator
Works out how long a loan takes to clear at a chosen repayment, and what it costs in interest along the way.
Savings goal timing calculator
Works out how long a savings target takes to reach at your current rate of saving.
Compound interest calculator
Shows how a balance grows over time with regular deposits and compounding interest.

All other debt calculators

Putting this calculator on your own site

This calculator can be embedded on a business website, branded to match it, with a call to action that sends the enquiry to that business rather than collecting anything here.