Price a session
| Wheel | House edge | Exact | Expected loss |
|---|
Why the wheel and not the bet
A European wheel has 37 pockets and pays a single number 35 to 1. Put one unit on one number and you win 35 once in 37 tries and lose one the other 36 times, which is a loss of 1/37 per unit staked. Now spread the same unit across six numbers on a six line, paid 5 to 1. The arithmetic lands in exactly the same place. That is not a coincidence: the wheel pays every bet as if it had 36 pockets while actually having 37, and the missing pocket is the whole house edge.
The American wheel adds a double zero, so it pays as if it had 36 pockets while having 38. One extra pocket, and the cost of every bet on the layout doubles. The one exception is the American five-number bet, which manages to be worse still at 7.8947%, and exists for no reason a player should accept.
The French rules, which are not the same rule
On a French wheel, an even-money bet that loses to zero is not simply lost. Under la partage half the stake is returned immediately. Under en prison the stake is held for one more spin and survives if the next spin wins.
Almost every published source quotes both as 1.35%. They are not the same number. We derive both: la partage is exactly 1/74, or 1.3514%, and en prison is exactly 19/1369, or 1.3879%. La partage is the better rule, because getting half back now beats a second chance at getting all of it back later.
Frequently Asked Questions
- Which roulette wheel is cheapest?
- A French wheel with la partage, at 1.3514% on even-money bets. The European wheel is 2.7027% and the American is 5.2632%, which is nearly four times the French figure.
- Are la partage and en prison the same?
- No, and almost every source says they are. La partage costs exactly 1/74, or 1.3514%. En prison costs exactly 19/1369, or 1.3879%. The difference is small but it is real, and we derive both.
- Does the bet you choose change the house edge?
- On a European or American wheel, no. Every bet on a European wheel costs 2.7027% and every bet on an American wheel costs 5.2632%, except the American five-number bet which is worse at 7.8947%. The wheel decides, not the bet.
- Why is the American wheel so much worse?
- One extra pocket. The double zero takes the wheel from 37 pockets to 38 while the payouts stay the same, and that single change doubles the cost of every bet on the table.
Every edge in this tool is injected from
roulette_math.py at build time as an exact fraction, and the
engine checks itself against published values before the page is written.
The arithmetic in your browser only multiplies those figures by your
stake and spin count; it does not estimate anything. Last computed
September 2026.