How We Calculate Gambling Odds & House Edge
The assumptions, formulas and source checks used for gambling odds, house-edge and expected-cost calculations on this site.
We show the rules and assumptions behind a number so readers can tell exactly what the calculation applies to.
House edge
When a wager has discrete outcomes with known probabilities and payouts, expected value is calculated by summing probability × net outcome across all possible results. House edge is the negative of player expected value expressed relative to stake.
RTP
Where a published theoretical RTP is used, we treat it as configuration-specific and do not convert it into claims about individual sessions.
Sports prices
Implied probability is derived from offered odds. Raw overround is the sum of outcome implied probabilities minus 100%; it should not automatically be described as the sportsbook’s realized profit margin.
Session-cost estimates
Expected loss = total action × house edge. The output is explicitly described as a long-run mathematical expectation, not a forecast.
Rule sensitivity
If a game’s edge changes with rules—blackjack is the clearest example—we avoid presenting one number as universal. Rule assumptions should appear beside the number.
Evidence vs interpretation
Primary rules, regulator statements and operator terms are treated as evidence. Explanatory conclusions are labeled as interpretation where appropriate.