KEY TAKEAWAYS
La partage and en prison are two roulette rules that soften the zero on even-money bets. On a European wheel with no special rule, the zero takes the entire stake on red, black, odd, even, high and low bets, which gives the casino an edge of 1 in 37, or 2.70%. La partage returns half the stake instead, which cuts the edge to 1.35%. En prison holds the stake for one more spin, and its edge is 1.35% or about 1.39%, depending on what happens if zero lands twice in a row.
Both rules apply only to even-money bets on single-zero wheels, and they cost the player something real: the house edge is lower, not gone. A casino may offer one rule, the other or neither, so the rules posted at the table decide which numbers apply.
This guide explains how each rule settles a zero, shows where the 1.35% and 1.39% figures come from, works through a $20 example, and lists what to check before you sit down.
What La Partage and En Prison Are
A European roulette wheel has 37 pockets: the numbers 1 to 36 and a single zero. The zero is green, and it belongs to neither red nor black, odd nor even, high nor low. That is why the zero is where the house edge comes from. An even-money bet wins on 18 of 37 pockets, which is 48.65%, yet it pays only 1 to 1, so the zero is the casino’s whole advantage on that bet. If you are new to the bet types, see how to play roulette.
La partage and en prison are zero rules that apply only to even-money bets: red or black, odd or even, and 1–18 or 19–36. They are usually found at French roulette tables, and a casino may offer one of them, the other, or neither. The name “la partage” is French for “the sharing”, and “en prison” means “in prison”.
Both rules soften the loss on a zero in different ways. La partage settles the bet immediately by splitting the stake between the player and the casino. En prison does not settle the bet at all; it holds the stake, and the next spin decides what happens. Both rules are described here for single-zero wheels, and the wheel itself still matters: see the European and American wheels for how the extra zero changes the numbers.
How Each Rule Settles a Zero
How la partage settles a zero
When the ball lands on zero, the casino returns half of every even-money stake and keeps the other half. A $20 bet on red that meets a zero comes back as $10, so the player loses $10 rather than $20. The result is final at once, and the returned chips can be used on the next spin. Because the zero lands once in 37 spins on average, the cost of the rule is half of 1/37, which is 1/74, or about 1.35%.
How en prison settles a zero
With en prison, a zero does not lose the bet; it locks the stake for one more spin. The dealer marks the chips as imprisoned, and the next spin decides them. If the bet would win on that spin, the stake is released with no profit. If the bet loses, the stake is lost. If zero lands a second time, the result depends on the table: some tables take the stake, some return half, and some keep it imprisoned for another spin. A second zero in a row is rare, about 1 in 1,369 spins, but the rule affects the exact house edge.
Where 1.35% and 1.39% come from
The figures follow from simple fractions. Under la partage, the player loses half a stake with probability 1/37, so the edge is 0.5 × 1/37 = 1/74, which is 1.3514%. Under en prison where a second zero loses, the imprisoned stake survives only if the next spin is a winner for the bet, which is 18 of 37 pockets. It loses on the other 19 pockets, made up of 18 opposing pockets plus the zero. The edge is 1/37 × 19/37 = 19/1369, which is 1.3879%. If a second zero returns half the stake or keeps it imprisoned, the edge works out to exactly 1/74 again. For the underlying idea, see how the house edge works.
Worked Example: A $20 Bet on Red
Suppose you bet $20 on red on a European wheel and the ball lands on zero. With no special rule, you lose the full $20. With la partage, you receive $10 back and lose $10. With en prison, your $20 stays on the layout and the next spin decides it.
On that next spin, the ball lands on red on 18 of 37 pockets, which is 48.65%. Your $20 is then returned with no profit. It lands on black on 18 pockets, or on zero on 1 pocket, which together is 19 of 37, or 51.35%. If a second zero loses at that table, you lose the $20 in both cases. So an imprisoned $20 is worth about $9.73 on average, which is $20 times 18/37, compared with the $10 you would have received from la partage.
Now weigh in how rarely zero lands. Across all spins, the expected loss on a $20 even-money bet is about $0.54 with no rule, $0.27 with la partage and $0.28 with en prison where a second zero loses. These are long-run averages over many bets, not a prediction for any one spin or session.
Common Mistakes and Myths About Zero Rules
The first myth is that la partage removes the house edge. It halves the edge on even-money bets, from 2.70% to 1.35%, but the casino still keeps an average of about $1.35 from every $100 wagered on those bets. Every house-banked bet keeps a negative expected value for the player.
A second mistake is assuming en prison and la partage are identical. They match at 1.35% only under some second-zero rules. Where a second zero takes the imprisoned stake, en prison is about 1.39%, which is slightly worse. Ask how the table treats a repeated zero before assuming either figure.
A third mistake is assuming the rule covers every bet. It does not. Straight-up numbers, splits, dozens and columns still lose the full stake on a zero and keep the standard 2.70% edge. Finally, lower edges tempt players toward betting systems on even-money bets, but a system cannot change the edge: see why the Martingale strategy fails.
What Each Rule Costs and What to Check at the Table
The cleanest way to compare the rules is the expected loss on each $1,000 wagered on a qualifying even-money bet. The figures assume a European single-zero wheel and apply only to even-money bets.
| Zero rule | What happens on a zero | House edge | Expected loss per $1,000 |
|---|---|---|---|
| No special rule | Stake is lost | 2.70% | $27.03 |
| La partage | Half the stake returned | 1.35% | $13.51 |
| En prison, second zero loses | Stake held one spin | about 1.39% | $13.88 |
The gap between 2.70% and 1.35% is real money over many spins, so an even-money bet at a la partage table is among the cheapest bets on a roulette layout. Before you buy in, check the table rules for the zero rule, how a second zero is treated, and whether the rule covers all even-money bets. Set a budget before you play, treat it as the cost of entertainment, and remember that legal age and the rules for casino gambling vary by state and venue.
It also helps to compare the whole table, not just the rule. A la partage table with a high minimum can still cost more per hour than a plain single-zero table with a low one, because the percentage applies to every dollar wagered. Expected loss is the amount wagered multiplied by the edge, so the stake size and the pace of play matter as much as the zero rule.
Where to Learn Next
Once you understand how the zero rules work, compare them with the rest of the casino. A 1.35% edge is low for a roulette bet, yet still higher than some other games, and the lowest house edge games and bets shows where each bet sits.
From here, the logical next step is to learn the other bets before judging the zero rule. A reader who knows what each roulette bet pays, and why the zero is the source of the edge, can read a table placard at a glance and tell at once whether a zero rule is on offer.
Frequently Asked Questions
