Enter what you owe, your card’s rate and how you plan to repay: a fixed amount each month, a set number of months, or only the minimum. You get the time it takes to clear the balance, the monthly payment, the total interest and a year-by-year breakdown. Each month’s interest is rounded to the nearest penny.
Take your latest statement
It shows your balance and your rates: the APR and, usually, the annual interest rate (p.a.). Enter one of them and say which. The calculator charges a twelfth of a rate p.a. each month; an APR already includes monthly compounding, so it takes the APR’s twelfth root instead.
Choose how you repay
Fixed amount: enter what you will pay each month and see how long it takes. In N months: enter a target and see the monthly payment. Minimum only: enter how your statement works out the minimum, for example 1% of the balance plus interest, and any amount it never goes below.
Read the things to check
If a payment does not even cover the month’s interest, the balance never falls, and the calculator says so. When you pay only the minimum, it also shows how much sooner you would finish by keeping to this month’s minimum.
Use the result
Copy the workings, export them as a CSV file or save the result to Priostack. Your recent calculations also stay on this device.
Monthly rate i: rate p.a. ÷ 12, or (1 + APR)^(1/12) − 1 for an APR.
Each month: interest = balance × i, rounded to the nearest penny, then balance = balance + interest − payment.
Payment to clear the balance in n months: balance × i ÷ (1 − (1 + i)^−n), rounded to the penny; the last payment clears what is left.
Example: £3,000 at 24.9% APR
The monthly rate is (1 + 24.9%)^(1/12) − 1 ≈ 1.8701%, so the first month’s interest is £56.10. Paying only a minimum of 1% of the balance plus interest, with a £5 floor, the first payment is £86.10 and it falls with the balance: clearing the card takes 28 years and 5 months and costs £5,394.95 in interest. Keeping to £86.10 a month instead clears it in 4 years and 9 months, with £1,899.94 of interest. To be clear in 2 years, pay £156.29 a month.
