Playing 300 spins at NZ$1 on a medium-volatility pokie with a 96% return, a NZ$20 bankroll hits zero in 86% of simulated sessions and a NZ$200 bankroll in none. The difference is the number of bets the money can absorb. The table below shows five bankroll sizes side by side.
Risk of ruin by bankroll
Bankroll in bets, not dollars
The question “how much money” has no answer until you pick the bet. NZ$100 is 100 bets at NZ$1 and 20 bets at NZ$5; the same money is a comfortable session in one case and a short one in the other. Counting the bankroll in bets removes the confusion.
What 300 spins do
| Bankroll | In NZ$1 bets | Hit zero within 300 spins | Median end balance | Ended above start |
|---|---|---|---|---|
| NZ$20 | 20 | 85.5% | NZ$0 | 12.8% |
| NZ$50 | 50 | 56.9% | NZ$0 | 26.4% |
| NZ$100 | 100 | 11.8% | NZ$64 | 32.8% |
| NZ$200 | 200 | 0.0% | NZ$164 | 33.0% |
| NZ$500 | 500 | 0.0% | NZ$464 | 33.0% |
At 20 bets the session is over in most cases. At 100 bets about one session in eight hits zero. At 200 bets none of 10,000 simulated sessions did. The median ending balance tracks the same line: NZ$0 for the two smallest bankrolls, NZ$63.50 for NZ$100, NZ$164.50 for NZ$200.
Notice the last column: the chance of finishing above your starting balance is roughly one in three once the bankroll is large enough to survive, and lower for small ones, which cannot recover from a cold run.
How these numbers were made. The simulations use a model pokie, not a real game: 96% return to player, medium volatility, a fixed bet on every spin, 20,000 simulated players per case. It shows how wagering behaves; it does not tell you what a particular pokie will do.
The rule of thumb
For 300 spins on a medium-volatility pokie, carry at least 100 bets, and 200 if you do not want to see zero. On a high-volatility game, add more. If your session money is less than that for the bet you want, lower the bet, not the number of spins.
Try your own
A bankroll also needs a stop: decide the loss at which you finish and write it down before you play. See limits and self-exclusion.
Questions readers ask
Does a bonus change the bankroll maths?
It adds balance but also wagering: you need the bets to survive both. See 40x wagering.
Is 300 spins long enough?
It is about 36 minutes at 500 spins an hour. Longer sessions raise the share who hit zero because the house edge keeps acting on the balance.