Roulette reference library

La Partage, En Prison and French Roulette

Learn how special zero rules can halve the edge on even-money bets.

Bottom line: On a single-zero game, la partage or a favorable en-prison rule can reduce the edge on red/black, odd/even, and high/low from 2.70% to about 1.35%.

La partage

When zero lands on an eligible even-money bet, half the wager is returned and half is lost. The zero event therefore costs only half a unit.

Because zero occurs once in 37 spins, the expected loss becomes one-half divided by 37, about 1.35%.

En prison

Instead of immediately returning half, the wager can remain imprisoned for a subsequent spin. Depending on the rule, a winning next result may release the stake without profit.

Multi-zero sequences and casino-specific settlement details can make en-prison variants differ. Read the actual rule.

Eligible bets

The favorable treatment normally applies only to even-money outside bets. Straight numbers, dozens, columns, and other wagers retain their usual edge.

A French-style layout or racetrack display does not by itself prove that la partage is offered.

Table selection

The best roulette choice is often the combination of single zero, a favorable zero rule, acceptable minimum, and manageable pace.

Special rules lower expected cost but do not make the game positive expectation.

Practical checklist

  • Confirm single-zero wheel
  • Ask whether la partage or en prison applies
  • Use only eligible even-money bets
  • Read repeat-zero treatment
  • Compare table minimum and pace
Scope and review

Rules, probabilities, and payouts apply only to the model stated on this page. Posted casino rules control when they differ. Last reviewed September 20, 2026.