Volatility
Volatility is how much a game's results swing around its average, from small frequent wins at the low end to rare large wins at the high end.
Also called slot volatility, high volatility, low volatility
Two games can have the same RTP and feel nothing alike. Volatility is the difference. A low-volatility game gives your money back in many small wins. A high-volatility game pays little for long stretches, then now and then pays a lot. Studios usually label slots low, medium or high. In maths terms, volatility is normally measured by the standard deviation, which is the square root of the variance.
Example. A dice game has a 1% house edge on every bet. At a 2x payout you win 49.5% of the time. At a 100x payout you win 0.99% of the time. Both return 99% on average. But at 100x there is about a 37% chance that 100 bets in a row all lose.
What people get wrong. Volatility is not the house edge, and a high-volatility game is not "due" after a dry spell. High volatility does not mean worse value either. It means a wider spread of results: more sessions that end at zero and a few that end far ahead. The long-run cost is set by the edge alone.
Match volatility to your bankroll and to how long you want to play.
Related terms
- Variance
Variance is a measure of how far results are spread around their average, worked out as the average squared distance from the expected value.
- Return to player (RTP)
RTP (return to player) is the share of all money bet on a game that it is built to pay back to players over a very large number of bets, shown as a percentage.
- House edge
The house edge is the share of each bet a casino expects to keep on average over the long run, equal to 100% minus the game's RTP.
- Bankroll
A bankroll is the fixed amount of money you set aside for gambling and can afford to lose, kept separate from the money you need to live on.
- Game provider
A game provider is the studio that designs and runs a casino game, which the casino then offers to players on its own site.