About the Credit Card Repayment Calculator
Credit card interest compounds monthly on whatever balance is left, so a fixed payment can take far longer to clear a debt than it first appears — and if the payment is too small, the balance can grow instead of shrink. This calculator simulates your balance month by month to show exactly how long payoff takes and how much interest you'll pay in total.
How it works
- Each month, interest is added to the balance at the monthly rate (your annual rate divided by 12).
- Your fixed payment is then subtracted.
- This repeats until the balance reaches zero, counting the months and adding up all the interest charged along the way.
Assumptions and behaviour
- Assumes no new spending is added to the card while you're paying it off.
- Assumes the same fixed payment every month and a constant interest rate.
- If your payment doesn't even cover the first month's interest, the calculator flags this clearly instead of showing a misleading payoff time — the balance would actually grow forever at that payment level.
Limitations
- Real cards may accrue interest daily rather than in one monthly lump, which can shift results slightly.
- Minimum payments on real cards are usually a percentage of the balance, not a fixed dollar amount — if your card works that way, your real payoff will look different from this fixed-payment model.
- Late fees, annual fees, and promotional 0% periods are not modelled.
Privacy
The calculation runs entirely in your browser. Nothing is uploaded or stored.
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