Roulette mathematics
One extra pocket nearly doubles the standard roulette edge.
The familiar payouts remain unchanged while the denominator of possible outcomes grows.
| Wheel | Pockets | Ordinary standard-bet house edge |
|---|---|---|
| Single zero | 37 | 2.70% |
| Double zero | 38 | 5.26% |
Example: red
Red covers 18 pockets and pays 1:1. On single-zero roulette, 18 of 37 outcomes win; on double-zero, 18 of 38 win. Zero—and 00 where present—are neither red nor black.
Special rules must be named
Some jurisdictions or tables apply la partage or en prison to even-money wagers. Those rules can change the effective edge and should be treated as a distinct ruleset rather than silently mixed into a generic roulette number.