Debt Repayment Calculator

Avalanche pays off the highest-interest-rate debt first and is mathematically the fastest, cheapest route out of debt — it minimises total interest paid. Snowball pays off the smallest balance first, which clears individual debts sooner and can build the motivation to stick with a plan. If you're confident you'll stay consistent either way, avalanche saves the most money. If you've struggled to stick with a payoff plan before, snowball's quick wins may keep you on track — even though it usually costs a little more in interest.

Both methods pay the minimum on every debt, then direct every extra dollar (plus any minimum payments freed up as debts are cleared) at one target debt. Avalanche targets the highest interest rate first, so less of your money goes to interest overall. Snowball targets the smallest balance first, so you clear individual debts faster, even if that debt isn't your most expensive one.

It depends on your balances, rates, and how much extra you add — but even a modest extra payment compounds quickly because it shrinks the balance interest is calculated on every month. This calculator shows your exact interest saved and months saved compared with paying only the minimums, based on the debts and extra payment you enter.

If a debt's monthly interest charge is larger than its minimum payment, the balance grows every month it isn't targeted with extra funds — this calculator flags any debt like this so you know to increase that minimum or make sure your extra payment reaches it. Without extra funds ever reaching it, that debt would never clear.

Yes. Because interest compounds on the remaining balance, targeting the highest-rate debt first (avalanche) minimises the total interest charged across all your debts. Targeting the smallest balance first (snowball) doesn't change the maths as much when balances and rates are similar, but it can matter a lot for motivation and reducing the number of accounts you're juggling.

As a rule of thumb, if a debt's interest rate is higher than what you'd reliably earn after tax from investing, paying it down first is the safer, guaranteed return. High-interest debt (credit cards, personal loans) almost always beats typical investment returns, so clearing it first is usually the better move before redirecting extra money into KiwiSaver or other investments.