How this calculator works
Each month the calculator adds interest (the APR divided by 12, times the remaining balance) and then subtracts your payment. It repeats until the balance reaches zero. Here r is the APR divided by 12.
If your payment is smaller than the monthly interest, the balance never goes down, and the calculator tells you so.
Worked example
Using sample inputs for a $5,000 balance at 22% APR with a $200 monthly payment:
Common questions
Why does the minimum payment take so long?
The minimum is often only a little above the monthly interest, so very little goes toward the balance itself.
What is the avalanche method?
You pay the minimum on every card and put any extra money toward the card with the highest APR first. This usually minimizes total interest.
What is the snowball method?
You put extra money toward the smallest balance first. It costs a bit more in interest than the avalanche method, but quick wins keep many people motivated.