Debt Payoff Plan Builder

Pick a method, add what you can, and get a real debt-free date

Paying minimums on several debts at once feels like running in place. The way out is to throw every spare pound at one debt until it dies, then roll that freed-up payment onto the next. This builder simulates exactly that, month by month, under either the avalanche method (cheapest) or the snowball method (most motivating), and tells you the date you become debt-free and the total interest you will pay along the way.

How it works

The tool runs a month-by-month simulation. Each month it charges interest, pays minimums, then aims the extra at one target debt:

For each month, for each debt:
  interest  = balance × (annual rate / 12)
  balance   = balance + interest − payment
Target debt:
  avalanche = the unpaid debt with the highest rate
  snowball  = the unpaid debt with the smallest balance
Extra payment → target debt only (on top of its minimum)
When a debt hits zero: its minimum + the extra
  roll onto the next target ("rolling snowball")
Repeat until every balance is zero.

Interest accrues monthly on each remaining balance, so paying high-rate debt down faster removes the most interest. The rolling payment is the engine: as each debt clears, the money it used to consume piles onto the next, accelerating every subsequent payoff.

Tips and example

Say you owe £4,000 at 22% and £6,000 at 9%, with £150 of minimums and £200 spare. Avalanche kills the 22% card first and saves the most interest; snowball would only differ here if the smaller balance had the lower rate. Always confirm every minimum actually exceeds that debt’s monthly interest — if it does not, the balance grows forever and the tool will warn you. Once you are debt-free, redirect the entire former payment into savings; you are already used to living without it, so the habit transfers cleanly. The simulation assumes fixed rates and payments, so treat fees and promo rates separately.