Debt Snowball Calculator

• Enter every debt with its balance, APR and minimum payment. Add as many as you need.
• Shows the payoff order, the date each debt clears, and your projected debt-free date.
• Compares against both minimum payments only and the avalanche method — no hiding the trade-off.
• The extra monthly amount does more work than the ordering. That is stated plainly in the results.

How the snowball works

The mechanics are simple, which is much of the appeal.

1. List every debt by balance, smallest first. Interest rates are ignored for the ordering.
2. Pay the minimum on everything.
3. Put every spare dollar at the smallest balance until it is gone.
4. Take that debt's entire payment — its minimum plus your extra — and move it to the next smallest.
5. Repeat. Each cleared debt makes the next payment larger.

The "snowball" name describes the payment, not the debt. Your total monthly outgoing never falls: as each account closes, its payment is absorbed into the attack on the next one. By the time you reach the last debt, you may be throwing several hundred dollars a month more at it than you started with.

Here is the rollover in action on the default figures — a $6,400 card at 23.9%, an $1,800 store card at 27.5%, a $14,200 car loan at 7.4% and a $21,500 student loan at 5.5%, with $300 a month spare:

What the snowball costs, and why people choose it anyway

The avalanche method — highest interest rate first — is mathematically optimal. It always produces the lowest total interest, because every extra dollar goes where it removes the most future cost. The snowball ignores rates entirely, so it usually costs more.

How much more? Usually less than people assume. On a typical mix of consumer debts the difference is often a few hundred to a couple of thousand dollars across a multi-year payoff — meaningful, but not decisive. Your own figures are compared directly in the results, so you can see the actual number rather than a generalisation.

Two situations narrow the gap to almost nothing:

• When the smallest balances also carry the highest rates, which is common, because small revolving balances tend to be on cards and large ones tend to be on secured loans. The two methods then produce nearly the same order.
• When the extra payment is large relative to the total debt, because everything clears quickly and there is less time for the rate difference to accumulate.

The argument for the snowball is behavioural, and it is a serious argument rather than a consolation prize. Debt payoff typically takes two to five years, and the main failure mode is not choosing the wrong order — it is stopping. Closing an account entirely is a discrete, visible event; watching a large balance drop by 4% is not. If clearing two accounts in the first six months is what keeps you going, the snowball may well produce the better real-world outcome even though it produces the worse spreadsheet outcome.

What the snowball is not is a mathematical improvement. Anyone who tells you it saves money is mistaken. It costs money, and it may be worth it.

The extra payment is doing most of the work

The ordering debate gets most of the attention and deserves the least. What actually determines whether you are debt-free in three years or eleven is how much you send above the minimums.

Try it in the calculator: change the extra payment from $300 to $500 and watch the debt-free date move. Then switch between snowball and avalanche at the same amount and watch how little changes by comparison. The extra payment is the lever; the ordering is a refinement.

Where an extra payment comes from is usually one of four places, and all four are worth examining before settling on a number:

• Reducing recurring spending — the effect compounds every month, unlike a one-off.
• Increasing income, through overtime, a raise, a side income or a job move.
• Selling something that is not earning its keep.
• Redirecting money currently going to a goal that can wait — though not, generally, an emergency reserve or an employer retirement match.

Why minimum payments are designed to fail you

On a credit card, the minimum payment is typically a percentage of the balance plus that month's interest, subject to a dollar floor. As the balance falls, the required payment falls with it — which stretches the payoff out enormously.

A $6,400 balance at 23.9% APR with a 1%-plus-interest minimum starts at around $191 a month. Paying only the minimum each month, the balance takes well over a decade to clear and costs several thousand dollars in interest. Paying a fixed $191 every month — the same starting amount, never reduced — clears it in about four years for a fraction of the interest.

Nothing changed except that the payment stopped shrinking. This is why the "minimum payments only" row in your results is usually so much worse than either strategy, and why the single most valuable habit in debt payoff is holding the payment constant as the balance falls.

Common mistakes

Continuing to use the cards. Paying down a balance while adding to it produces a plan that never finishes. The calculator assumes no new charges, and that assumption has to be true for the projection to hold.

Skipping the starter emergency fund. With no cash cushion, the next unexpected expense goes on a card and undoes months of progress. A small reserve — often one month of essential expenses — before attacking debt hard is a common and sensible sequence. The Emergency Fund calculator helps size it.

Giving up an employer retirement match. A 50% or 100% match is an immediate, guaranteed return that exceeds any consumer interest rate. Capturing the match first is almost always right, even while paying down debt.

Closing paid-off cards immediately. Closing an account reduces your total available credit, which raises your utilisation ratio and can lower your credit score, and eventually shortens your average account age. Leaving a paid-off card open and unused generally serves you better — though if keeping it open means you will use it, close it and accept the score effect.

Consolidating without changing behaviour. A consolidation loan that clears the cards, followed by new card balances, leaves you with both. Consolidation is a tool for lowering the rate, not a substitute for the plan.

Frequently asked questions