European vs American Roulette

The two main roulette wheel designs, distinguished by whether the wheel has one zero (European) or two zero pockets (American), which sharply changes the built-in house edge.

Definition

European roulette uses a wheel of 37 pockets (numbers 1-36 plus a single 0), giving the operator a house edge of 2.70% on virtually every bet. American roulette adds a second zero pocket (00) for 38 pockets, which raises the house edge to 5.26% because payouts are still calculated as if the extra pocket did not exist. The playing layout and bet types are almost identical between the two; the only meaningful mechanical difference is that extra 00 pocket, yet it nearly doubles the operator's long-run mathematical advantage. Because the edge is baked into the odds, no betting pattern removes it, and over many spins the maths favours the operator regardless of short-term swings.

Worked example

You place 100 separate $1 straight-up bets. On a European wheel each number pays 35:1 but has a 1-in-37 chance, so your expected loss is about $2.70. On an American wheel the same 35:1 payout is set against a 1-in-38 chance, and your expected loss roughly doubles to about $5.26. Same game, same bet size, nearly twice the theoretical cost simply because of the second zero.

Why it matters

For a learner, this is the clearest single illustration that game rules, not luck, determine long-run cost: one extra pocket doubles the edge. For anyone working in the industry, wheel choice is a headline product and compliance detail, and understanding the 2.70% vs 5.26% split is foundational to explaining game maths honestly.

Related

Note: The 2.70% and 5.26% figures are standard for straight bets; French/European tables with La Partage or En Prison rules lower the effective edge on even-money bets to about 1.35%.