Debt Avalanche Calculator - Highest-Rate Payoff

Estimate debt avalanche payoff months by directing payments at the highest interest balance first. Cut interest cost before you refinance.

Enter the high-rate balance, its annual interest rate, and the total monthly payment you can put toward that balance.

Debt Avalanche Calculator - Highest-Rate Payoff
Months ≈ ceil( −ln(1 − B × r / P) / ln(1 + r) ), where r is the monthly rate and P is the monthly payment.

About the debt avalanche calculator

The debt avalanche method ranks balances by interest rate and sends every extra dollar to the costliest debt while other accounts receive only their minimums. That order minimizes interest if you actually stick with it. The debt avalanche calculator estimates how many months a chosen monthly payment takes to clear one high-rate balance under compound interest, which is the first step in an avalanche plan and a useful bound when several cards are rolled into a single target payment. The closed-form payoff time for a fixed payment is n = −ln(1 − B × r / P) / ln(1 + r), then rounded up to a whole month. B is the balance, r is the annual rate divided by 1,200, and P is the payment. If P is not larger than B × r, interest equals or exceeds the payment and the balance never falls. A $10,000 balance at 22% with $500 a month takes 26 months. $5,000 at 18% with $300 takes 20 months. $20,000 at 25% with $1,000 takes 27 months. Avalanche is the interest-minimizing cousin of the debt snowball, which ranks by smallest balance instead. Avalanche usually costs less; snowball often feels faster because small accounts close sooner. Use avalanche when the rate gap is wide — a 25% card versus an 8% installment loan — and you can tolerate leaving a small cheap balance open. Use the estimate to size the payment you must send to the top-rate account after funding minimums elsewhere. This estimate treats one balance and one payment. A true multi-account avalanche rolls the freed minimum onto the next-highest rate after each payoff, which shortens later accounts. Fees, penalty APRs, variable rates, and skipped payments are not modeled. Credit-card minimums that shrink with the balance free cash over time; entering a fixed P is conservative if you will keep paying the same dollar amount. Recalculate when the rate, the target payment, or the balance changes, and compare the month count with a refinance or balance-transfer offer. If a transfer fee plus a lower rate beats 26 months of 22% interest, the avalanche number is the baseline you needed. The debt avalanche calculator will not prioritize accounts for you; sort by APR yourself, then use the months figure as the plan for the current top target.

Debt avalanche payoff examples

Months use the standard fixed-payment formula, rounded up, at a monthly rate of APR ÷ 12.

InputsPayoffNote
$10,000 at 22%; $500 monthly26 monthsPayment clears the high-rate balance in just over two years.
$5,000 at 18%; $300 monthly20 monthsA smaller card still needs 20 months at this payment.
$20,000 at 25%; $1,000 monthly27 monthsA large 25% balance remains expensive even with a four-figure payment.

How to estimate a debt avalanche payoff

  1. List debts by APR and enter the current highest-rate balance.
  2. Enter that account’s annual interest rate as a percent.
  3. Enter the monthly amount you will send to that account (minimum plus extra).
  4. Select Calculate Avalanche Payoff, then repeat for the next-highest rate after this one is gone.

Debt avalanche FAQ

What is the debt avalanche method?

You pay minimums on every account and put all extra money toward the highest interest rate. After that balance hits zero, the extra payment rolls to the next-highest rate. The goal is to cut interest, not to close the smallest account first.

How are payoff months calculated?

The calculator uses n = −ln(1 − B × r / P) / ln(1 + r) with r = APR / 1,200 and then rounds up. That is the standard number of periods for a fixed payment on a compound-interest balance.

Why is my payment rejected?

If the payment is not larger than the first month of interest, the balance never falls. Raise the payment or lower the rate (for example with a transfer) until P exceeds B × APR / 1,200.

Should I use avalanche or snowball?

Avalanche usually costs less interest. Snowball ranks by smallest balance and can be easier to stick with. Compare both month counts if motivation is the constraint; compare interest if the rate gap is large.

Does this model several cards at once?

It estimates one target balance and one payment. After that account is paid, add its former payment to the next-highest rate and run the estimate again. Multi-account roll-down is not simulated in a single run.