Credit Card Installment Calculator (Add-On Rate)
Monthly amortization, total interest and true effective rate of a card installment plan.
Tool inputs stay in your browser · optional AI search sends your query
Good to know: Add-on interest = principal × monthly rate × months. Because you pay down the principal every month, the true (effective) rate is much higher than the add-on rate. Estimate for planning only, based on the numbers you enter. Your bank or provider’s statement is the final word.
How to use it (step by step)
- 1Fill in the boxes: “Purchase amount”, “Monthly add-on rate (%)”, “Months”, “One-time processing fee”. Example numbers are already there so you can see how it works; replace them with yours.
- 2The result updates instantly as you type (on a phone it is below the boxes).
- 3The bold line is the main answer. Tap Copy next to any value to copy it.
Words to know
- Interest
- The extra money you pay for borrowing, like a rental fee for using someone else’s money.
- Add-on rate
- Interest calculated on the FULL original amount for every month, even though you pay it down. That is why the true rate is almost double the advertised one.
- Effective rate
- The real cost of a loan or fee once everything is counted, so you can compare offers fairly.
- Amortization
- Your fixed monthly payment that slowly pays off both the interest and the borrowed amount.
- Principal
- The amount you originally borrowed, without the interest.
- Percentage
- A part out of 100. 25% of 200 = 50.
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