How this calculator works
This simplified model charges one month of interest before applying each fixed payment. It assumes no new purchases, fees, promotional changes or changes to the payment. The last payment is reduced to the amount due. Actual cards often accrue daily interest, so Canadian and US statements can differ. Estimates beyond 1,200 months are rejected.
Formula
i = r/12; interest = opening balance × i; payment = min(fixed payment, balance + interest); new balance = balance + interest - payment. Repeat until the balance is zero. Total interest is the sum of monthly charges. The fixed payment must exceed the initial monthly interest.
Worked example
Paying $200 a month on $5,000 at 19.99% clears the balance in 33 months. Total paid is $6,521.02, including $1,521.02 of interest, and the final payment is $121.02.
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Frequently asked questions
Can I use the minimum payment from my statement?
Only as a fixed amount for this estimate. Many minimum payments fall as the balance falls; that changing schedule is outside this model.
Why is a payment rejected when it covers interest?
A payment equal to or below the first month's interest does not reduce the starting principal under this model.
Does this account for a grace period?
No. Interest accrues monthly from the opening balance. Grace periods and daily balance rules require the card agreement and transaction history.