Debt Snowball vs Avalanche Calculator Ireland

What this calculator is designed to do

This calculator compares two common ways of directing extra money towards ordinary consumer debts once the required payments on every debt are being maintained:

• Debt avalanche: direct the extra payment to the debt with the highest APR first.
• Debt snowball: direct the extra payment to the debt with the smallest balance first.

When a debt is cleared, this calculator rolls the payment that had been going to that debt into the next target. The overall monthly debt budget therefore stays broadly constant until the debts are cleared.

The two methods answer slightly different questions. Avalanche focuses on the cost of interest. Snowball focuses on clearing smaller balances earlier. Under the simplified assumptions in this calculator, directing extra money to the highest interest rate is mathematically designed to minimise interest, while the snowball can produce an earlier first cleared account.

Important: priority debts come before a snowball or avalanche plan

A generic snowball or avalanche calculator is not appropriate for deciding whether to pay your mortgage, rent, electricity, gas, Revenue debt, court obligations or other essential/priority commitments.

MABS guidance separates priority payments from secondary debts and places particular emphasis on keeping appropriate accommodation, essential utilities and other basic necessities protected. The BPFI–MABS protocol similarly says mortgage debt should be prioritised over other debt and that other debts should then be considered according to the consequences of non-payment.

If you are already behind on essential or secured payments, are unable to make the required repayments, or are borrowing to cover basic living costs, use a full budget and seek help rather than relying on the ranking produced here. MABS provides free and confidential money and debt advice in Ireland.

How the avalanche works

Every month the calculator:

1. applies one month of interest to each remaining balance using the APR you entered;
2. makes the stated minimum payment on each debt;
3. sends the rest of your fixed monthly debt budget to the remaining debt with the highest APR;
4. once that debt is cleared, rolls the freed payment into the next highest-rate debt.

If two debts have the same APR, the smaller balance is targeted first as a tie-breaker.

This is why avalanche usually reduces total interest: expensive balances are attacked earlier.

How the snowball works

The monthly process is the same, except the extra payment is directed to the smallest remaining balance.

When the smallest debt disappears, its payment is rolled into the next-smallest balance. That can create visible milestones sooner, even though a higher-rate debt may continue accumulating interest in the background.

If two balances are equal, the higher APR is targeted first as a tie-breaker.

Minimum payments matter

The minimum-payment figures are not cosmetic. They determine the starting monthly debt budget and how much each non-target debt receives while another debt is being attacked.

The CCPC warns that credit-card balances can take years to clear when only minimum repayments are made because a large share of the payment may go towards interest. It recommends paying more than the minimum where affordable and stopping new card spending while trying to clear the balance.

Real credit-card minimums often change as the balance changes. This calculator deliberately uses the fixed monthly payment you enter so that both strategies can be compared on the same basis.

What APR means in this model

For modelling, Compound converts each annual percentage rate into a simple monthly rate by dividing it by 12 and applies that rate to the outstanding balance each month.

Real lenders can calculate interest daily, include fees, use variable rates, apply promotional periods or calculate APR using conventions that are more detailed than this model. The output is therefore a planning estimate, not a lender settlement figure.

The extra-payment assumption

“Extra monthly payment” means money available after all of the minimum payments entered in the table.

If your debt minimums total €500 and you enter €200 extra, the model starts with a €700 monthly debt budget. As debts are cleared, their former minimum payments are not treated as spare spending money: they are rolled into the next target.

This is important. If you stop rolling freed payments forward, the payoff time will be longer than the result shown here.

A repayment plan still needs a real household budget

The CCPC’s debt action plan recommends identifying all debts, building a realistic budget and working out affordable repayments. Before committing to an aggressive extra payment, leave enough room for essential bills and unexpected costs.

A mathematically fast plan that causes missed rent, mortgage, utility or other essential payments is not a sustainable plan.

What this calculator does not model

It does not include:

• new borrowing or new card spending;
• late fees, account fees or penalty interest;
• 0% balance-transfer promotional periods;
• changing minimum-payment percentages;
• variable interest rates;
• settlements, restructures or negotiated repayment arrangements;
• legal priority between creditors;
• mortgage arrears or personal-insolvency arrangements.

It also assumes each payment reaches the debt in the same monthly cycle used for the interest calculation.

If the numbers are not affordable

If your required payments are already difficult to meet, a snowball or avalanche comparison may be the wrong starting point. The CCPC directs people struggling with repayments to MABS, and MABS can help review the full financial position and deal with creditors.

The calculator is most useful when you are already meeting the required payments and want to understand how directing an additional affordable amount changes the path to becoming debt-free.

Worked example

Imagine three ordinary consumer debts:

• €1,500 at 5% APR;
• €5,000 at 22% APR;
• €10,000 at 8% APR.

If the required monthly payments are all being maintained and you have €200 extra each month, avalanche directs that extra €200 towards the 22% debt first because it is the most expensive balance to carry. Snowball directs it towards the €1,500 balance because it is the smallest.

The snowball may produce the psychological milestone of clearing one account sooner. The avalanche is designed to reduce the amount of time that the highest-cost balance remains outstanding. Once either target is cleared, the money that had been going to it is rolled into the next target.

The exact euro difference depends on every balance, APR and payment you enter, which is why the side-by-side result is more useful than a general rule of thumb.

Method and limitations

Compound applies one month of interest using APR ÷ 12, makes the fixed monthly payments entered on all active debts, then sends the remaining fixed debt budget to the strategy target. When a debt is cleared, its former payment remains in the total debt budget and is redirected.

The model does not reproduce lender-specific daily interest, changing card minimums, promotional 0% periods, late fees, restructures or legal priority between creditors. It is designed for debts whose required payments are already being maintained.

Frequently asked questions

Which method usually costs less interest?

When every debt receives its required payment and the same fixed debt budget is used, directing extra money to the highest APR first is mathematically designed to minimise interest under the calculator’s simplified assumptions.

Why would anyone use the snowball?

Some people prefer the earlier visible milestone of clearing a small balance. Behaviour matters in real repayment plans, but the calculator deliberately shows the financial trade-off rather than declaring one method universally best.

Should I include my mortgage?

Not in this consumer-debt comparison. Mortgage arrears and other priority commitments should be handled separately because the consequences of non-payment are different.

What if a minimum payment changes every month?

Use a realistic fixed payment for scenario planning and update the calculation periodically. Real card minimums can change as the balance changes.

Related Compound tools

Use the Loan Repayment Calculator for one conventional loan, the Net Worth Calculator to see debt in the context of your assets, and the Emergency Fund Calculator when deciding how much spare cash can safely go to accelerated repayments.