Credit Card Optimizer Calculator
Optimize how you split a fixed monthly budget across several cards. Paying the highest rate first minimises total interest and clears your cards fastest.
A worked example
Running this tool on current national benchmarks (Federal Reserve / Freddie Mac via FRED (St. Louis Fed)) — swap in your own numbers to see how the result moves.
- Debt 1 — balance
- $9,000
- Debt 1 — rate
- 22%
- Debt 1 — minimum payment
- $180
- Debt 2 — balance
- $4,000
- Debt 2 — rate
- 15%
- Debt 2 — minimum payment
- $90
- Debt 3 — balance
- $6,000
- Debt 3 — rate
- 8%
- Debt 3 — minimum payment
- $110
- Extra monthly payment
- $200
43 months · $5,519 total interest
- Total debt$19,000
- Total interest$5,519
- Interest saved vs minimums$9,574
The math behind it
Given a fixed monthly budget across several cards, the optimizer allocates it the cheapest way: pay every card's minimum, then send all remaining money to the card with the highest interest rate. Interest is applied to each card first, then payments, month after month. As each card clears, its minimum is freed and rolled onto the next-highest-rate card. This highest-rate-first allocation minimizes total interest and clears your cards in the fewest months for that budget.
Assumptions & limits
- The budget is split highest-rate-first after all minimums are covered.
- Each card's APR is fixed throughout.
- No new charges are added while you pay the cards down.
- Minimums are always paid; only the surplus is optimized.
- Your total budget must exceed combined monthly interest to make progress.
Common questions
What is the optimal way to split payments across cards?
Mathematically, pay the minimum on every card so none goes delinquent, then put every extra dollar on the card with the highest APR until it is gone — then repeat with the next-highest. Spreading extra money evenly across cards feels fair but costs more interest. This calculator applies the optimal split automatically.
Does a bigger balance ever change the order?
Not for minimizing interest. The optimizer orders strictly by rate, not balance, because a dollar of the highest-APR debt always costs the most to carry. If you would rather clear whole cards fastest for motivation, the snowball calculator orders by balance instead.
Should I keep paying the minimum on low-rate cards?
Yes. Paying every minimum keeps all accounts current and protects your credit; only the money left over is concentrated on the top-rate card. Skipping a minimum to overpay elsewhere risks late fees and penalty rates that wipe out the savings.