Calculator guide
Debt Avalanche Calculator: Highest APR First, Less Interest
Published by Sonya · DebtPayoff.cc · Published: 2026-07-08 · Updated: 2026-10-04
Reviewed for calculation accuracy against the published method and automated tests
This avalanche calculator page explains highest-APR ordering. Extra money goes to the fastest interest rate after every minimum is paid, even when that account is not the one you could close first.
What avalanche means in the calculator
The sort key is APR, not balance. With these inputs the 27.49% card receives the extra payment before the 23.99% card and before the 15.99% card, after all three minimums are covered.
A zero balance drops out of the order. Its old minimum joins the extra budget on the next month and is then aimed at the next highest APR.
Worked avalanche: highest APR is not the smallest balance
Inputs: $900 at 15.99% with a $35 minimum, $4,200 at 27.49% with a $126 minimum, and $2,600 at 23.99% with a $78 minimum. Extra budget is $100. Combined minimums are $239, so the first-month payment is $339.
Avalanche clears the $4,200 card in month 25, then the $900 card and the $2,600 card in month 31. Estimated interest is $2,775.26. Snowball on the same inputs clears the $900 card in month 8 but costs $3,048.29 and finishes in month 32.
The modeled gap is $273.03 and one month. It exists because snowball lets the 27.49% balance wait while it finishes the small 15.99% card. Month-one interest on the $4,200 balance alone is about $96.22 under the monthly approximation (balance times 27.49% divided by 12).
| Strategy | Balance that reaches zero first | Months | Interest |
|---|---|---|---|
| Avalanche | $4,200 card at 27.49%, month 25 | 31 | $2,775.26 |
| Snowball | $900 card at 15.99%, month 8 | 32 | $3,048.29 |
| Minimums only | No extra payment | 55 | $5,399.20 |
Statements use a different interest clock
Many card issuers compute interest from a daily or average daily balance. The daily interest on a real statement can therefore differ from this page, which uses a monthly APR divided by 12 so two strategies can be compared on one set of assumptions. A statement can show a different interest charge even when the payment amounts match.
If the gap between the model and two or three statements is larger than fees and new purchases can explain, trust the issuer ledger and update the inputs. Do not keep a payoff month that the statements have already contradicted.
When APR order is the wrong first move
Avalanche does not help if the extra amount is unaffordable, a minimum is already below the interest, or an account is in collections. Those situations need the creditor or a qualified adviser, not a different sort order.
A promotional APR should be modeled as its own scenario through the expiration date, then again at the post-promotion APR. Averaging the two rates hides the month the avalanche target may change. Results stay in the browser and are educational only, not financial advice.
- Highest APR receives extra money only after every minimum.
- No account, upload, or server-side plan storage.
- Educational only. Not a payoff quote.
Common questions
Who is the debt avalanche method best suited for?
Avalanche works best when you are motivated by numbers rather than quick wins, when the interest gap between your debts is large, or when one high-APR balance is eating most of your payment. If you can stay consistent for several months without needing to see an account closed, avalanche usually costs less overall.
How do I handle a promotional APR that will expire?
Model the promotional period as its own scenario using the promotional APR, then run a second scenario using the post-promotion rate. Do not average the two rates into one number, because that hides the month when the avalanche target may switch. The calculator lets you rerun the plan with updated APRs whenever terms change.
What happens when two debts have the same APR?
The calculator applies a fixed tie-breaking rule so identical inputs always produce the same order. In practice, two debts at the same APR cost the same per dollar of balance, so the tie-break does not change your total interest. It exists to keep exports and shared links reproducible.
Why does avalanche take longer to close the first account?
Because the highest-APR debt is often not the smallest one. In the worked example on this page, avalanche targets a $4,200 card at 27.49% first, which takes 25 months to close, while snowball would close a $900 card in month 8. The slower first win is the tradeoff for lower total interest.
Avalanche-specific limits
Ordering is highest APR after minimums. Interest for the worked example is the production engine's monthly approximation, not a daily-balance recreation of a card statement.
Fees, penalty APRs, hardship plans, and prepayment rules are outside the model. The $273.03 gap is true only for the three balances, rates, minimums, and $100 extra payment listed above.
- APR order can leave the smallest balance open for many months.
- Daily interest can change the dollar result without changing the order.
- Do not average a promotional APR with the go-to rate.
- Educational only. Not financial advice.
Primary sources
- Debt action plan tool — Consumer Financial Protection Bureau (Last verified: 2026-10-04)
- How credit-card interest is calculated — Consumer Financial Protection Bureau (Last verified: 2026-10-04)