En Prison Rule in Roulette Explained | Casino Guide

What is the En Prison Rule in Roulette?

The En Prison rule is one of the most advantageous rules available at a roulette table. Its name, French for 'in prison,' perfectly describes what happens to your bet. This rule comes into play only on even-money wagers - bets like Red/Black, Odd/Even, or High/Low - when the ball lands in the green '0' pocket. Instead of the house instantly taking your losing bet, your stake is locked on the table for one more spin.

Think of it as a second chance. Your money is held captive, awaiting the result of the next spin. If that spin results in a win for your original bet (for example, you bet on Red, and the next spin is Red), your entire stake is returned to you. You don't win any extra money, but you don't lose your original bet either. If the next spin is a loss, the house then claims the imprisoned stake.

How En Prison Works: A Step-by-Step Example

Let's walk through a clear scenario:

1. You place a $10 bet on Black, an even-money bet.

2. The croupier spins the wheel, and the ball lands on 0.

3. The croupier places a marker on your bet, indicating it is now 'en prison'.

4. On the next spin, the ball lands on a Black number. You win! The croupier removes the marker, and your original $10 stake is returned to you.

5. Alternatively, if the ball had landed on a Red number, you would lose your imprisoned $10 stake.

The Huge Impact on the Roulette House Edge

The primary reason savvy players seek out the En Prison rule is its significant effect on the house advantage. In standard European Roulette (with a single zero), the house edge is 2.7%. However, when the En Prison rule is active on even-money bets, that edge is halved to just 1.35%. This makes it one of the best bets in any casino.

"Any seasoned roulette player understands that finding a table with the En Prison rule is a top priority. It's the single most effective rule for lowering the house's built-in advantage on outside bets, giving you a much fairer game."

Here’s how it compares to other common roulette variations:

En Prison vs. La Partage: What's the Difference?

Another player-friendly rule found in French Roulette is 'La Partage.' It's often confused with En Prison, but there's a key difference. The La Partage rule also applies to even-money bets when zero hits. However, instead of imprisoning your bet, you immediately get half of your stake back, and the other half is lost. For example, on a $10 bet, you'd instantly receive $5 back. Mathematically, the long-term effect on the house edge is identical (1.35%). The choice between them is a matter of player preference: do you want a guaranteed small loss (La Partage) or a riskier chance to recover your entire stake (En Prison)?

Where to Find the En Prison Roulette Rule

The En Prison rule is a hallmark of French Roulette. You'll most commonly find it at casinos in Europe, particularly in Monte Carlo. Some high-limit rooms in other parts of the world, as well as certain online casinos, also offer French Roulette with this rule. It is almost never found on American Roulette tables, which feature both a '0' and '00', making their house edge significantly higher. Always check the table rules before playing to see if this favorable condition is available.

This rule is particularly sought after by strategic players who understand its impact on the long-term house edge. When browsing the expansive game library of a top-tier online casino, look for specific French variants in the live dealer section. These digital tables often implement En Prison to attract serious enthusiasts, providing a level of mathematical fairness that is hard to match. By reducing the house advantage on even-money bets to as low as 1.35%, it remains one of the most player-friendly features in the gambling industry today.