Credit Card Balance Calculator

I wanted to have a way to know about how much of each payment was going towards interest and how much of each payment was going towards principle and a rough estimation for what my balance should be after each payment so I wrote a calculator that would give me exactly this data. I compared it with some other financial calculators and found it fairly accurate.

The two problems are that it assumes (like other calculators I tested) that the payment goes in at the absolute last day of the payment period, and it assumes all months have 30 days.

I may tweak it later, but it is “close enough” for the uses I wanted. I don’t know if anyone else can find a use for it, but if you think you can, check it out here.

Oh, if you enter negative values for the payment, you can use it to calculate interest on an account, but you must enter a positive “term” to look at because it would never be “paid off”. In this case the portion toward principle and portion toward interest columns aren’t quite what you’d expect. Also, it assumes daily compounding still which is not how most savings accounts work.