Credit Card Interest Calculator
Last updated: October 15, 2026
Estimate monthly interest, payoff time, and total interest for a fixed credit card payment.
Estimated payoff time
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- First month interest: —
- Estimated total interest: —
On this page
Quick summary: Estimate monthly interest, payoff time, and total interest for a fixed credit card payment.
Read the method, example and limitations
Updated reference sections in this guide are in English.
Guide language: English. Updated October 15, 2026.
What this calculator estimates
Credit Card Interest Calculator
Inputs and units
Use the units shown for Card balance ($), APR (%), Monthly payment ($). Required fields cannot be blank. Use zero only where that field and the model allow it. Select Calculate after changing a scenario.
Method and assumptions
Each month, interest equals the current balance multiplied by APR/1200. Subtract the fixed payment, reducing the final payment to the amount due. Count completed payments and total interest. A positive balance needs a payment greater than its monthly interest.
Worked example
A 1,000 balance at 0% with 100 paid monthly is repaid in ten months. A 50,000 balance with a 10 payment at 0% is explicitly beyond the 100-year calculation limit.
Limitations
This monthly model excludes new purchases, daily-average balances, minimum-payment changes and fees. The simulation limit is not reported as a completed payoff.