Math & fairness
How the math behind a slot game works, in plain language, and how fairness is checked in regulated markets.
Four ideas to know
Random number generation
Each game round is decided by a random number generator, so that one round does not depend on the one before. In regulated markets, game software and random number generators must be tested in line with that market’s technical standards and testing rules before release.
RTP
Return to player is the percentage of money staked that a game is designed to return over a very long period of play. It is a long-run average, not a promise about any session.
Volatility
Volatility describes how a game's returns are spread. Two games with the same RTP can behave very differently over a short session.
Testing before release
Gambling software supplied for use under a Gambling Commission licence must meet the Commission’s technical standards and be tested in line with its testing strategy before release.
Why it matters
Slot games are defined by mathematics. Testing checks that a game's random number generator and its math behave as documented, so that operators and regulators can rely on the figures a supplier publishes.
Gambling software supplied for use under a Gambling Commission licence must meet the Commission’s technical standards and be tested in line with its testing strategy before release.
Specification figures for each title, including RTP, maximum win and volatility, are listed on its game page.
Fairness is not a promise of results
Gambling is for adults and can be harmful. A fair game still involves risk, and no game can guarantee a result. Operators are responsible for player protection. Responsible gaming.
Math and fairness questions
Does a higher RTP mean a player will win more?
No. RTP is a long-run average across a very large number of rounds. It says nothing about the result of any single session.
Can a game round be influenced by previous rounds?
A properly working random number generator produces results that are independent of earlier rounds. That is one of the things that testing in regulated markets is designed to check.
Why do two games with the same RTP feel different?
Because of volatility: how returns are spread across rounds. See games by volatility.
Who checks that the math is what it says?
In regulated markets, game software and random number generators must be tested in line with that market’s technical standards and testing rules before release. Gambling software supplied for use under a Gambling Commission licence must meet the Commission’s technical standards and be tested in line with its testing strategy before release.
Where can I read more?
Our glossary defines the terms used on this website, and our responsible gaming page lists organisations that can help.