Ten thousand sessions run in your browser and shown as a histogram, because one average hides almost everything that matters.
Worked example. £200 played at £1 a spin for 1,000 spins is £1,000 of turnover, more than the bankroll, because winnings are staked again.
| Starting bankroll | £200 |
| Turnover if the money lasts | £1,000 |
| Expected cost of that turnover | −£40 |
Enable JavaScript to run ten thousand sessions and see the spread of outcomes rather than this single average.
How this works
Each simulated session starts with your bankroll and spins at your stake until the spins run out or the money does. Wins are drawn from a payout model built for the volatility class you choose, scaled so the long-run return matches the RTP you enter.
Ten thousand sessions are run and sorted into the histogram. The bars to the right of your starting bankroll are sessions that finished up; the rest finished down or went bust. The shape is the answer: on a high-volatility slot most sessions lose and a few win big, which is exactly why the average misleads.
This is a model of a slot's behaviour, not a copy of any specific game's maths, which studios do not publish in full. Use it to compare settings against each other, not to predict a particular session.
Play with money you can afford to lose. Casino games are built to return less than is staked over time. Set a budget and use your account's deposit limits. Free, confidential support is available from GamCare on 0808 8020 133. More on staying in control.