Book 2 · Money Math

Debt Payoff

Enter a balance, an APR, and your monthly payment — see months to zero, total interest, and how to order multiple debts.

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Enter your balance, APR, and monthly payment.

Rank multiple debts

Enter up to five debts. Avalanche pays the highest APR first (least interest). Snowball pays the smallest balance first (fastest wins).

NameBalanceAPR %
Pick an order — avalanche saves interest, snowball builds momentum.
From the book — Chapter 4 of The Money Math Workout. Months to payoff = −ln(1 − r·B / P) ÷ ln(1 + r), where r is the monthly rate (APR ÷ 12 ÷ 100), B is the balance, and P the monthly payment. If P is less than r·B the balance grows — the payment doesn't even cover the interest.

Educational only — not financial advice. Assumes a fixed APR and payment. Everything stays in your browser.