En Prison is a French roulette rule that can lock an even-money bet after zero instead of taking it immediately. On the next spin, if the original bet wins, the stake is usually returned without profit. If it loses, the stake is lost. Like La Partage, En Prison can reduce the effective edge on qualifying even-money bets to about 1.35%.
Quick Facts
- En Prison means “in prison.”
- It usually applies only to even-money bets.
- It triggers when the ball lands on zero.
- The original stake is held for another spin or later settlement.
- A successful follow-up result usually returns the stake only, not profit.
- House rules vary on what happens if zero lands again.
- It is less common and more procedural than La Partage.
Plain Talk
En Prison is the delayed version of zero protection.
You bet on red. Zero lands. Instead of taking your chips, the dealer marks the bet as “in prison.” Your bet is trapped for the next spin. If red hits next, you normally get your original stake back. If black or another losing result hits, the stake is gone.
This rule is easy to describe but more complicated to operate than La Partage because the bet remains unresolved after the zero spin.
The Wizard of Odds roulette guide groups En Prison with the favorable French roulette rules. The practical settlement still depends on posted house rules, which is why formal rules such as the Massachusetts roulette rules and approved rule repositories like the Nevada approved games page matter when casinos define how roulette variants are offered.
How It Works
A normal En Prison sequence looks like this:
- You place a qualifying even-money bet.
- The ball lands on zero.
- The dealer marks the bet as imprisoned.
- The bet stays locked for the next spin.
- If the original bet wins on the next spin, your stake is returned.
- If the original bet loses on the next spin, the stake is taken.
- If zero lands again, the result depends on the table’s house rules.
| First spin | Your original bet | En Prison action | Next spin | Common settlement |
|---|---|---|---|---|
| Zero | $20 on red | Bet locked | Red | $20 stake returned, no profit |
| Zero | $20 on red | Bet locked | Black | $20 lost |
| Zero | $20 on red | Bet locked | Zero again | Depends on posted rules |
The “zero again” rule is the detail players must check. Some tables keep the bet imprisoned. Some may settle differently. Do not assume every En Prison table is identical.
Scope guard: this page explains En Prison only. For the simpler half-back settlement, read La Partage rule. For the wider French format, read French roulette rules.
Roulette Table Example
You place $50 on low numbers, 1–18.
The ball lands on 0.
The dealer announces or marks the bet as En Prison. Your $50 remains tied to the original low bet.
Next spin: 14 lands.
Because 14 is low, your original condition wins. The dealer returns your $50. You do not receive $50 profit. You escaped the zero loss; you did not win the next spin like a fresh live bet.
Now change the next spin to 29. Your low bet loses, and the $50 is taken.
This is why En Prison feels more dramatic than La Partage. The outcome is stretched across two spins.
From the Casino Side:
En Prison is a procedure-heavy rule. The dealer must clearly mark the imprisoned bet, protect it from player interference, remember its original condition, and settle it correctly after the follow-up spin.
That creates more opportunity for confusion than La Partage. Players may think they are owed profit. Dealers may need to explain that the recovery spin returns the stake only. Supervisors may be called when zero appears twice or when the rule is not understood.
From a game manager’s view, En Prison is a good rule for knowledgeable players but not always ideal for speed. It slows settlement, creates pending bets, and adds training demands. That is one reason many casinos prefer La Partage if they offer a zero-protection rule at all.
Surveillance wants the marker and locked bet visible. A chip stack that remains on the layout after a resolved spin is normally suspicious unless procedure clearly explains why it is still there.
Common Mistakes
- Thinking En Prison pays profit when the follow-up spin wins.
- Forgetting that the original stake is still at risk.
- Assuming all zero-again cases are handled the same way.
- Believing En Prison applies to inside bets.
- Treating the locked bet as a fresh free spin.
- Touching or moving an imprisoned bet.
- Confusing En Prison with La Partage.
Hard Truth
En Prison gives the player a second chance to recover the stake. It does not give the player a free chance to beat roulette.
FAQ
What does En Prison mean in roulette?
It means an even-money bet is held after zero and resolved on a later spin, usually the next spin.
Do I win profit if my imprisoned bet wins next spin?
Usually no. The common rule returns your original stake only. Always check the posted table rules.
Which bets qualify for En Prison?
Usually even-money bets: red/black, odd/even, and high/low.
What happens if zero lands again?
That depends on the house rules. Some tables keep the bet imprisoned. Others may settle differently. Check before playing.
Is En Prison better than La Partage?
Mathematically, both can produce about a 1.35% effective edge on qualifying even-money bets, but settlement timing and zero-again rules can differ.
Is En Prison common in casinos?
It is less common than standard roulette rules and often appears in French-style, European-style, or selected high-limit/live roulette environments.
Can En Prison be used with Martingale?
It can be combined with any bet-sizing pattern, but it does not remove table limits, bankroll risk, or negative expectation. Read why roulette systems fail before trying progressions.
Deeper Insight
En Prison is psychologically different from La Partage.
La Partage is clean pain: zero lands, half is gone, half comes back. The result is finished.
En Prison creates suspense. The player gets a rescue attempt. That can feel better because the loss is not final yet. But the math is not sentimental. The player’s original stake is still exposed to the next outcome.
This delayed settlement can also distort memory. Players remember the dramatic recoveries and forget the trapped bets that died on the next spin. They may describe the rule as “getting another chance,” which is true, but incomplete. The chance is not free. It is a conditional attempt to recover a stake already damaged by zero.
Operationally, En Prison also shows why rules are more important than table myths. The same red bet can have different long-term cost depending on what the table does after zero. That is real. A hot-number board is not.
A disciplined player uses En Prison as a rule-selection benefit, not a reason to increase bet size. The correct reaction to a better rule is not automatically “bet more.” It may be “pay less for the same entertainment.”
Formula / Calculation
A simplified En Prison edge on even-money bets is commonly treated like La Partage when the rule gives equivalent zero protection:
Normal single-zero even-money edge:
$$EV = -\frac{1}{37} = -2.70%$$
With equivalent En Prison protection:
$$EV \approx -\frac{0.5}{37} = -1.35%$$
Probability of the first spin landing zero:
$$P(zero) = \frac{1}{37} = 2.7027%$$
Expected loss on $1,500 total action at 1.35%:
$$Expected\ Loss = 1500 \times 0.0135 = 20.25$$
Expected loss on the same action at standard European 2.70%:
$$Expected\ Loss = 1500 \times 0.0270 = 40.50$$
Formula Explanation in Plain English
En Prison reduces the cost of the zero on even-money bets. Instead of zero being a full immediate loss, the bet gets a recovery path. When that recovery structure is equivalent to half-back value, the effective edge is about half the normal single-zero edge.
The rule changes settlement after zero. It does not change the wheel, the number sequence, or the chance of the next color.
Related Reading
Pair this page with La Partage rule and French roulette rules to understand the protected-zero family. For the base numbers, use roulette odds and roulette odds chart. For long-term cost, read roulette house edge and house edge with En Prison. To model session swings, try the variance simulator and compare results with the expected loss calculator.