Credit Card Payoff Calculator
When several cards are competing for your money, the order you attack them in changes how much interest you pay. This planner takes a list of cards with their balances, APRs, and minimum payments plus a single extra payment, then simulates two well-known strategies month by month: the avalanche, which targets the highest APR first, and the snowball, which clears the smallest balance first. It reports the payoff time and total interest for each and the interest the avalanche saves.
Formula
Each month: interestᵢ = Bᵢ × (APRᵢ/12/100); Bᵢ ← Bᵢ + interestᵢ − payment
- Bᵢ
- Remaining balance on card i
- APRᵢ
- Annual percentage rate on card i
- payment
- Minimum payment plus any extra routed to the priority card
- priority
- Highest APR (avalanche) or smallest balance (snowball) first
How it works
- Add each card with its balance, APR, and minimum payment, then enter one extra monthly amount to throw at the debts beyond the minimums.
- Every month the simulation charges interest and pays the minimum on each card, then routes all of the extra payment to the priority card — highest APR for avalanche, smallest balance for snowball — rolling freed-up money forward as cards are cleared.
- It runs both strategies to completion and reports the months and total interest for each, plus how much interest the avalanche order saves versus the snowball.
Worked example
Card A: $5,000 at 22% APR, $150 minimum; Card B: $2,000 at 18% APR, $60 minimum; with $200 extra per month.
- Avalanche targets Card A (22%) first, then Card B; total interest works out to about $1,359.31 over 23 months.
- Snowball targets Card B ($2,000 balance) first, then Card A; total interest is about $1,524.03, also over 23 months.
- Interest saved by avalanche: 1,524.03 − 1,359.31 = $164.72.
Both plans clear the debt in 23 months, but the avalanche pays about $1,359.31 in interest versus $1,524.03 for the snowball, saving roughly $164.72.
Frequently asked questions
- What is the difference between the avalanche and snowball methods?
- The avalanche directs your extra payment at the highest-APR card first to minimise interest, while the snowball clears the smallest balance first for quicker psychological wins. This tool simulates both so you can weigh cost against motivation.
- Which strategy saves the most money?
- The avalanche almost always pays the least total interest because it kills the most expensive debt soonest. The calculator reports the exact interest saved versus the snowball for your specific cards.
- How does the extra payment work across multiple cards?
- Each card gets its minimum every month; the extra amount is added on top and aimed entirely at the current priority card. Once a card is paid off, its freed-up money rolls into the next one, accelerating the remaining payoff.
- Does the simulation assume no new spending?
- Yes. Balances only go down as you pay them; no new charges are added. If you keep using the cards, your real payoff will take longer and cost more interest than the plan shows.