En prison rule in roulette
En prison is a roulette rule where, if zero lands, your even-money bet is “imprisoned” for the next spin instead of being lost. Win that spin and you get your original stake back with no profit; lose it and the stake goes. It cuts the house edge on even-money bets to roughly 1.4%.
By the Best Casino Apps UK team. Last checked .
Key takeaways
- En prison freezes an even-money bet for one more spin when zero comes in.
- A win on the next spin only frees your stake; it pays no profit.
- The house edge on those bets falls from 2.70% to roughly 1.39%.
- Check the game rules to see what happens if zero lands twice in a row.
- Meaning
- “In prison” (French)
- Applies to
- Red/black, odd/even, 1–18/19–36
- What happens on zero
- Stake held for the next spin
- Best outcome when held
- Stake returned, no winnings
- Typical edge on even-money bets
- About 1.39%
How the en prison rule works, spin by spin
On a normal single-zero table, a bet on red simply loses when the ball settles in the green pocket. Under en prison, the dealer (or the game software) leaves the chips on the table and marks them as held. Nothing is paid and nothing is taken yet. The imprisoned bet then rides on the following spin, and its fate depends on that result alone.
- You stake £20 on black and the ball lands on zero.
- Your £20 stays on the black box, flagged as imprisoned. You can’t move or withdraw it.
- The wheel spins again. You can add fresh bets around it as usual.
- If black wins, the £20 returns to your balance with no profit. If red wins, the £20 is lost.
- If zero lands again, the game’s own rule decides: many versions treat it as a loss, while some keep the stake imprisoned for another spin.
Only the six even-money boxes qualify. Numbers, splits, corners, dozens and columns are settled in the usual way when zero lands, which means they lose.
What en prison does to the house edge
Without the rule, an even-money bet on a 37-pocket wheel carries a 2.70% house edge, because zero turns up once in 37 spins on average and takes the whole stake. With en prison, that zero only costs you if the next spin also goes against you, which happens 19 times in 37 when a second zero counts as a loss. Multiply 1/37 by 19/37 and the edge comes out at about 1.39%.
| Table type | What happens on zero | Approx. house edge |
|---|---|---|
| European, no special rule | Even-money bets lose | 2.70% |
| French with la partage | Half the stake returned | 1.35% |
| French with en prison (second zero loses) | Stake held for one more spin | 1.39% |
| American (0 and 00) | Even-money bets lose | 5.26% |
In pounds: £1,000 of even-money bets costs about £27 on average at a plain European table and about £14 under en prison. Those are long-run averages, not predictions for any single session.
En prison compared with la partage
The two French rules land in almost the same place mathematically but feel very different. La partage settles straight away: half back, half gone, move on. En prison is all or nothing on the next spin, so you either recover the full stake or lose it. Some land-based French tables let the player choose between the two when zero lands; online games normally apply one rule automatically, and the help screen says which.
Spotting en prison inside a casino app
Open a French roulette table and tap the ‘i’ or the three-line menu, then look for a heading about zero or special rules. Phrases such as “imprisoned”, “en prison” or “stake held for the next spin” confirm it. During play, an imprisoned chip is usually drawn with a marker or moved onto the line of the box, and the bet panel shows it as held rather than settled. Our French roulette apps page describes the layout in portrait and landscape.
Because a held bet belongs to an unfinished round, closing the app or losing signal doesn’t cancel it. UK technical standards require games to handle interrupted play, and the round is resolved under the game’s rules, normally visible in your history when you reopen it. If a held bet seems to have vanished, check the game’s history screen before contacting support; the games won’t load page covers what to do when a table freezes mid-round.
Your on-screen balance excludes an imprisoned stake until it is settled, so don’t be surprised if the figure looks £20 lighter for one spin.
UK rules on mobile roulette that still apply
Every online roulette round in Great Britain must last at least five seconds, and the game can’t spin by itself: you confirm each round. A rule like en prison reduces the average cost of even-money bets, yet the casino keeps an edge on every spin. Decide your budget before opening the app, and use a deposit limit or reality check to keep track. Help is available any time from the National Gambling Helpline on 0808 8020 133.
Related terms
The wheel behind both French rules is described under single-zero roulette, and RTP explains how an edge becomes a return figure. The roulette apps guide and the glossary index cover the rest.
18+. Gambling should be entertainment that costs money, not a way to make it. Set a deposit limit before you play: how to set limits. Free, confidential help: National Gambling Helpline 0808 8020 133.
Frequently asked questions
What does en prison mean in roulette?
En prison means your even-money bet is held on the table for one more spin when the ball lands on zero, rather than being lost. If the next spin wins for your bet, the original stake is returned without any winnings. If it loses, the stake is gone. The rule covers red/black, odd/even and high/low only. It appears mainly on French roulette, which our French roulette apps page explains in detail for phone players.
What happens if zero lands twice under en prison?
It depends on the game’s rules, so read the help screen. In the most common version, an imprisoned bet loses if zero lands again on the following spin, which gives a house edge of about 1.39% on even-money bets. Some versions keep the bet imprisoned for further spins until a non-zero result frees or loses it. The exact wording sits under the zero or special-rules heading inside the game. Our house edge entry shows how these small rule changes affect the cost.
Is en prison better than la partage?
Neither is clearly better; they cost almost the same over time. La partage gives an edge of about 1.35% and settles immediately with half your stake back. En prison is about 1.39% in its usual form and resolves on the next spin with either the full stake back or nothing. If you prefer instant, predictable settlement, la partage suits you; if you don’t mind waiting a spin, en prison is equivalent. Compare both in our la partage entry.
Can I remove an imprisoned bet in a casino app?
No, an imprisoned bet stays on the table until the next spin decides it. The chip is locked, and the clear or undo buttons only affect new chips you place. That is part of the rule: you accepted it when you bet on a table that uses en prison. If you want to stop playing, you can leave after the held bet is settled, and the result will appear in your history. The how to play roulette on mobile guide explains these buttons.
Do live roulette tables in UK apps use en prison?
A few live French tables may use en prison, but most live roulette streamed to UK apps is standard European roulette without it. The only reliable check is the rules page for that specific table, which you open from an icon on the stream. Live tables also set their own betting timer and limits. Our live roulette apps page explains how to read a live table’s rules and how much mobile data a stream uses.
Does en prison apply on American roulette?
Usually not. American roulette has both a zero and a double zero, giving a 5.26% edge on most bets, and app versions rarely include en prison. Some American-style games offer a similar ‘surrender’ rule that returns half of even-money stakes on 0 or 00, which lowers that bet’s edge to about 2.63%, still far worse than a French table. Our American roulette apps page explains the double-zero layout and its cost.