Dozen and column bets
Dozen and column bets are roulette outside bets that each cover twelve numbers and pay 2:1, so a winning €10 chip returns €20 in profit plus the original stake. A dozen is a block of consecutive numbers, while a column runs down the long side of the layout. Neither group contains the zero, which is where the house edge on both bets comes from, and on a single-zero wheel the bet wins 12 times in 37 over the long run.
How the 2:1 payout and the edge are calculated
A dozen or column bet would be fair if it paid 2:1 on a wheel of 36 pockets, because twelve numbers are exactly a third of thirty-six. The single zero adds a thirty-seventh pocket that belongs to no group, so the true odds against a win are about 2.08 to 1 while the casino still pays 2 to 1.
Over 37 one-unit bets, a player expects twelve wins worth two units each and twenty-five losses of one unit, which nets out to a loss of one unit, or 2.70% of the money staked. On an American wheel the extra double zero pushes that figure to 5.26%, with a win chance of 12 in 38 rather than 12 in 37.
The edge is the same as on a straight-up number.
Which numbers each group covers
The grid below shows how the standard layout splits 1 to 36 into dozens and columns, and where the zero falls; any single dozen and any single column always overlap on four numbers.
| Bet | Numbers covered | Payout |
|---|---|---|
| First dozen | 1 to 12 | 2:1 |
| Second dozen | 13 to 24 | 2:1 |
| Third dozen | 25 to 36 | 2:1 |
| Any column | Every third number, e.g. 1, 4, 7 up to 34 | 2:1 |
| Zero (and 00) | In no dozen or column | Both bets lose |
What dozen and column bets are confused with
Players often assume a column is somehow safer than a dozen because its numbers are spread across the whole range, yet the two are mathematically identical in coverage, payout and edge.
A second mix-up concerns French roulette, where the La Partage rule halves the loss on even-money bets when zero lands; dozen and column bets are normally excluded from that rule, so they keep the 2.70% edge, though table rules vary between operators and are worth reading before play.
Covering two dozens at once does not beat the house either.
