Zero does not always take the whole even-money wager.
On a single-zero wheel, La Partage and En Prison can materially reduce the edge on red/black, odd/even and high/low wagers.
La Partage
When zero appears on an eligible even-money wager, the player loses only half the stake. On a standard single-zero wheel this cuts the house edge on those bets from about 2.70% to 1.35%.
En Prison
Instead of immediately losing half, the wager may be “imprisoned” after zero. Under common French-style treatment, if the next spin wins the wager is released without profit; if it loses, the stake is lost. Exact handling of a second zero can vary by casino, so the written rule matters.
| Single-zero rule | Even-money edge | Other ordinary bets |
|---|---|---|
| Normal | 2.70% | 2.70% |
| La Partage / French-style treatment | 1.35% | 2.70% |
What does not change
La Partage does not improve a straight-up number, split, street, corner, dozen or column under standard French treatment. The favorable rule applies to eligible even-money wagers.
Verification note
“European roulette” does not guarantee La Partage or En Prison. Verify the actual zero rule shown in the game help, felt signage or written casino rules.