How this calculator works
Choose whether you want to know how long it’ll take to pay off a balance at a given monthly payment, or how much you’d need to pay each month to hit a specific payoff timeline. For the first mode, this calculator simulates your balance month by month — charging interest, then applying your payment — for an exact answer, rather than relying on an approximate formula.
The formula
Each month: interest = balance × (APR / 12) balance = balance + interest payment = min(monthlyPayment, balance) balance = balance − payment ...repeat until balance = 0 Guard: if monthlyPayment ≤ first month's interest, the balance never shrinks.
Worked example
A $5,000 balance at 24% APR, paying $200/month:
- Simulating month by month, the balance reaches $0 after 36 months
- Total interest paid over that time: $2,000.57
- The final (36th) payment is just $0.57 — the last sliver of the balance
Frequently asked questions (FAQ)
Why does paying only the minimum take decades?
Minimum payments on most cards are calculated to barely exceed that month's interest charge, so almost none of it goes toward the actual balance. Even a modest bump above the minimum dramatically cuts both the payoff time and the total interest you pay.
What's the difference between the avalanche and snowball payoff methods?
With multiple debts, avalanche pays off the highest-interest-rate balance first (saves the most money); snowball pays off the smallest balance first (builds momentum and motivation). Avalanche is mathematically optimal; snowball tends to help people stick with the plan.
Does this account for new purchases added to the balance?
No — this assumes you stop adding new charges and only make the payments you enter. Continuing to use the card while paying it down will slow your progress and increase total interest paid beyond what's shown here.
What if my payment doesn't even cover the interest?
If your monthly payment is less than or equal to the interest charged that month, your balance will never shrink — it can even grow. This calculator flags that case and shows the minimum payment needed to start making real progress.
How much does a higher APR really cost me?
A lot, especially on a slow payoff. On a $5,000 balance paid at $200/month, moving from 15% to 24% APR adds real months to your payoff time and hundreds of dollars in extra interest — try both rates here to see the difference.