Casino maths hub
Casino Game Maths: RTP, Odds and Volatility
Casino game maths separates what a game does over many rounds from what you may see today. RTP and expected value describe long-run averages; volatility describes how unevenly results arrive; probability and odds describe the chance of specific outcomes.
RTP and house edge
RTP is the theoretical percentage returned across a very large number of plays. House edge is the complementary percentage: for a 96% RTP game, the theoretical house edge is 4%. Neither number predicts a short session.
Probability, odds and expected value
Probability expresses how likely an event is. Odds compare favourable and unfavourable outcomes. Expected value multiplies each possible result by its probability and adds the values together.
Volatility and variance
Two games can share an RTP while feeling completely different. Lower volatility tends to produce smaller, more frequent results; higher volatility tends to concentrate return in rarer, larger results.