Minimum Payment Impact Calculator

Minimum payment impact on credit card payoff time and interest

Most people searching for a minimum payment impact calculator are trying to answer one practical question: if I keep paying only the minimum payment on my credit card, how long will it take to get out of debt and how much interest will I end up paying? This calculator is built for that exact decision. It models a credit card balance month by month, adds interest, applies the minimum payment rule, and tracks how many months it takes until the balance reaches zero. It also shows what changes when you add a fixed extra amount on top of the minimum each month.

To use it, enter your current balance and your card’s APR. Then optionally enter an extra amount you can pay each month. If you do not enter an extra amount, the calculator still gives you the minimum payment outcome, and it also shows an example of what a small extra payment could do. The two minimum payment settings are there because many credit cards set the minimum as a percent of the balance, but also enforce a minimum floor amount. The default values are common in practice, but your statement may differ. If you know your issuer’s minimum formula, replace those defaults and recalculate.

The results are meant to be decision ready. The first result is the “minimum only” payoff timeline and total interest paid, because that is the baseline reality people underestimate. If you add an extra payment, the calculator then shows a second payoff timeline and interest total, plus the time saved and interest saved versus minimum only. The key takeaway is mechanical: when you pay only the minimum, your payment often shrinks as the balance shrinks, which keeps the balance alive for far longer. A modest fixed extra amount counters that shrinking payment and accelerates the payoff curve.

Assumptions and how to use this calculator

• Interest is compounded monthly using APR divided by 12, and the model assumes the APR stays constant for the payoff period.
• The minimum payment is calculated as the greater of (minimum percent of the current balance) and (minimum payment floor amount), which is a common credit card rule.
• Extra payment, if provided, is added on top of the minimum payment every month and is assumed to be paid consistently on time.
• No new purchases, cash advances, fees, or penalty rates are included; adding new spending can materially extend payoff time.
• If the payment ever fails to cover at least the month’s interest, the balance will not decline reliably; in that case, the calculator warns that the payment level is not sufficient.

Common questions

Why does paying the minimum take so long?

Minimum payments are designed to keep you current, not to eliminate the balance quickly. When the minimum is a percentage, the payment typically declines as the balance declines. That means you may be paying a similar amount of interest for many months, and the principal reduces slowly. The result is a long tail where small balances linger and keep generating interest.

What minimum payment rule should I use?

Check your statement or card terms. Many issuers use something like “X% of the balance or a minimum of Y.” If your statement specifies a different method, adjust the percent and floor values to match. If you cannot find it, the defaults are reasonable for a rough estimate, but treat the output as directional rather than exact.

What if my APR changes or I get a promotional rate?

This calculator assumes one APR for the whole period. If you have a temporary promo APR that later changes, the payoff time and interest will differ. A simple workaround is to run the calculator twice: once using the promo APR to see best case, and once using the post promo APR to see the long run cost if the balance remains.

What if I sometimes miss a payment or pay late?

Late payments can trigger fees and higher penalty APRs, which will increase interest and extend the payoff period. This calculator does not model those events. If late payments are realistic for you, consider the results optimistic. The more accurate approach is to assume a higher APR and add a buffer to your extra payment goal.

How much extra should I pay to make a real difference?

The highest leverage move is a consistent fixed extra amount, even if small, because it prevents your payment from shrinking as the balance shrinks. Run a few scenarios by changing the extra payment field in small steps. Focus on the time saved and interest saved versus minimum only, and choose the highest extra payment you can sustain without breaking your cash flow.