Every position on a roulette layout pays less than a mathematically fair return would require. This gap creates the house edge in roulette btc games. Base rates are determined by wheel structure, and bet types determine if any adjustments are applied.
There is a 2.7% house edge on a European single-zero wheel with 37 positions. There is consistency because payouts are calculated to be exactly one unit below a fair return. Bets on straight-ups cover a single position and pay 35 to 1. A fair return for a 1 in 37 probability is 36 to 1. This edge of 2.7% can be calculated based on a one-unit shortfall across 37 trials. It pays 17 to 1 if you split a bet on two positions. For 2 out of 37, the return would be 17.5 to 1. There is a proportional shortfall in both cases. It applies to all even-money bets, including streets, corners, six-lines, dozens, and columns. Each bet type produces a different payout ratio, but not a different edge.
Why does the five-number bet stand apart?
On a double-zero wheel, one bet type breaks the otherwise uniform 5.26% edge. The five-number bet covers zero, double-zero, one, two, and three and pays 6 to 1. A proportionally fair payout for five positions on a thirty-eight-position wheel would be 6.6 to 1. The gap between 6 to 1 and 6.6 to 1 is larger in proportion than the gap that produces 5.26% on other bet types.
- Five-number house edge: approximately 7.89%
- All other double-zero bet types: 5.26%
- The five-number bet is the only position on a double-zero layout where the edge deviates from the uniform rate
- No equivalent asymmetric bet exists on a single-zero wheel because there is only one zero pocket
How do special table rules reduce the edge on selected bets?
The edge on even-money bets is lowered on some single-zero tables. Layout rules do not apply to everything. Those positions are red, black, odd, even, high, and low that pay even money. Once the ball lands on zero, the shares return half the stake. Half of the unit is recovered rather than lost. The zero outcome now costs half of what it used to, reducing the effective edge from 2.7% to about 1.35%.
En prison holds the full even-money stake on the wheel for one additional spin when zero appears. If the held bet wins on the following spin, the original stake is returned in full with no profit. If it loses, the full stake is forfeited. The long-run effect of en prison on edge is equivalent to la partage, producing approximately 1.35% on even-money bets under the same zero-frequency assumption.
Inside bets on the same table receive no adjustment under either rule. A straight-up bet on a table offering la partage still carries a 2.7% edge. The rule is confined to even-money positions.
Table rules such as la partage and en prison can reduce the edge below the wheel’s structural rate, but only for the bet types they cover. No rule can reduce the edge below zero, because the zero pocket itself is what creates the asymmetry between probability and payout. Removing the zero would produce a fair game with no edge.
