Debt Snowball vs Avalanche Calculator
Type in each card or loan — balance, APR, minimum payment — and what you can add each month. The calculator runs the debt snowball (smallest balance first) and the debt avalanche (highest APR first) on the same numbers and shows the debt-free date, the total interest and the payoff order for each, side by side. It is free, there is no sign-up, and nothing you type leaves this page.
How the two methods differ
Both methods pay every minimum every month. They differ only in where the extra money goes. The snowball sends it to the smallest balance, so a debt disappears early and its minimum rolls onto the next one. The avalanche sends it to the highest APR, which is where each dollar cancels the most interest. On most real debt lists the avalanche costs less in total and the snowball clears the first debt sooner; the gap between them is often small when the APRs are close, and large when one balance carries a card-level rate.
The calculator does not pick for you. It shows the interest difference in dollars and the finish dates in months, and badges the order that wins on each count, so the choice is yours with the trade-off in front of you.
How the arithmetic works
Each month, in this order: interest is added to every balance at APR ÷ 12; every minimum is paid, capped at what is owed; then the extra amount and every minimum freed by a paid-off debt go to the target debt, spilling over to the next one when the target clears. The monthly total stays fixed for the whole plan, which is what makes the snowball roll. Amounts are kept in whole cents and rounded half-up, the same way the Debt Ladder app does it — the two use the same engine and are tested against the same schedule.
Card issuers mostly charge interest on a daily balance rather than once a month, so expect small differences from a statement. The direction and size of the result hold.
When the numbers say "never"
If a minimum payment is smaller than the month's interest on that debt, the balance grows instead of shrinking. The calculator flags that debt in the list. If the whole plan stalls at your payment, it says so rather than inventing a date; raising the extra until a date appears tells you the smallest monthly amount that actually works.
Frequently asked questions
Is the debt avalanche always cheaper than the snowball?
On the same debts and the same monthly payment, the avalanche never costs more interest than the snowball, because each extra dollar goes to the balance charging the highest rate. The difference can be small when APRs are similar, and both orders can finish in the same month. Run your own numbers to see the gap in dollars.
Why would anyone choose the snowball if it costs more?
The snowball clears a whole debt sooner, which cuts the number of payments to juggle and gives a visible win early. Some people keep going longer that way. The calculator shows how many months earlier the first payoff lands and what the choice costs, so you can decide whether that is worth it.
Does this calculator store my debts?
No. There is no account and no database. The share link packs your debts into the part of the address after #, which browsers never send to a server; the link itself is the only copy.
Why does the calculator say a debt never gets paid off?
Because its minimum payment is less than one month of interest at the current balance, so paying only the minimum makes the balance grow. Adding extra money, or clearing other debts so their minimums roll onto it, fixes that; the calculator shows the date as soon as the plan works.
Is this financial advice?
No. It is arithmetic on the numbers you enter. It does not know your income, your other obligations or your options, and it does not recommend products. For advice about your situation, speak with a qualified professional or a non-profit credit counsellor.
Keep the plan going in Debt Ladder
Debt Ladder is the app behind this calculator. It uses the same payoff engine, then keeps the plan alive: a monthly check-in to log what you actually paid, extra payments on any day for any amount, and a debt-free date that moves as you go. Private and on your phone — no account, no bank linking, no ads. Scan the QR code above to carry this plan into the app.