A roulette column bet covers 12 numbers in one vertical track of the printed 1–36 grid and pays 2 to 1. It wins on 12 of 37 pockets on a single-zero wheel and 12 of 38 pockets on a double-zero wheel. Zero and double zero belong to no column, which creates the casino advantage.
The three columns have identical probability and payout. Their number patterns differ, but none is mathematically better.
Which numbers are in each column?
Viewed from the player’s end of a standard layout:
| Column box | Numbers covered | Pattern |
|---|---|---|
| First column | 1, 4, 7, 10, 13, 16, 19, 22, 25, 28, 31, 34 | Numbers congruent to 1 modulo 3 |
| Second column | 2, 5, 8, 11, 14, 17, 20, 23, 26, 29, 32, 35 | Numbers congruent to 2 modulo 3 |
| Third column | 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36 | Multiples of 3 |
The wager is placed in one of the three boxes marked 2 to 1 at the end of the number grid. A chip on a dozen box does not buy a column, even though both wagers cover 12 numbers and pay the same price.
The roulette table-layout guide shows the physical betting positions. The wheel-layout guide explains why printed-grid neighbors are not neighboring pockets on the wheel.
Exact probability by wheel type
Let:
- (W=12), the number of winning pockets;
- (N), the total number of wheel pockets;
- (z=N-36), the number of zero pockets.
The win probability is:
[ P(\text{win})=\frac{12}{N} ]
| Wheel | Total pockets | Win probability | Loss probability |
|---|---|---|---|
| Single zero | 37 | (12/37=32.4324%) | (25/37=67.5676%) |
| Double zero | 38 | (12/38=31.5789%) | (26/38=68.4211%) |
| Triple zero | 39 | (12/39=30.7692%) | (27/39=69.2308%) |
Triple-zero roulette is not available everywhere, but when offered it makes every standard column less favorable because the extra zero is another losing pocket without a larger payout.
Payout and total return
A column pays 2 to 1. On a $10 winning wager:
- net profit: $20;
- original stake returned: $10;
- total amount returned: $30.
“2 to 1” is not the same as “2 for 1.” The first states net profit relative to stake. The second would describe total return and would be an inferior payment.
Official Massachusetts roulette rules define a column as 12 numbers in one printed column, require the wager to be placed in the box at the bottom of that column, and list a 2-to-1 payout. The full table procedure appears in the Massachusetts Gaming Commission roulette rules.
House-edge derivation
For a one-unit column wager paying 2 to 1, expected value is:
[ EV=\left(\frac{12}{N}\times2\right)-\left(\frac{N-12}{N}\times1\right) ]
Simplifying:
[ EV=\frac{24-(N-12)}{N}=\frac{36-N}{N}=-\frac{z}{N} ]
The house edge is therefore:
[ House\ Edge=\frac{z}{N} ]
Results:
| Wheel | EV per unit | House edge |
|---|---|---|
| Single zero | (-1/37) | 2.7027% |
| Double zero | (-2/38) | 5.2632% |
| Triple zero | (-3/39) | 7.6923% |
This is the same standard edge as most other conventional bets on the same wheel. The column’s broad coverage does not create a discount. It only changes how often the player wins and how much each win pays.
Fair odds versus casino odds
Fair net odds equal losing pockets divided by winning pockets.
For single-zero roulette:
[ Fair\ Odds=\frac{25}{12}=2.0833\text{ to }1 ]
For double-zero roulette:
[ Fair\ Odds=\frac{26}{12}=2.1667\text{ to }1 ]
For triple-zero roulette:
[ Fair\ Odds=\frac{27}{12}=2.25\text{ to }1 ]
The table pays only 2 to 1. That gap is the price of the zero pocket or pockets. The payouts-versus-true-odds guide applies the same test to other roulette wagers.
Betting two columns does not beat the wheel
A popular system places one equal unit on two columns. This covers 24 numbers and produces frequent net wins.
On a single-zero wheel with one unit on each of two columns:
- 24 pockets produce one winning column and one losing column;
- net result on those pockets is +1 unit;
- the uncovered column’s 12 numbers plus zero produce a -2-unit result.
Expected value per spin is:
[ EV=\frac{24}{37}(+1)+\frac{13}{37}(-2) ]
[ EV=\frac{-2}{37}\approx-0.05405\text{ units} ]
Total action is two units, so the edge on action remains:
[ \frac{2/37}{2}=\frac{1}{37}=2.7027% ]
The system wins on 64.86% of spins but loses twice the base unit on every uncovered result. A high winning-spin percentage is not the same as positive expectation.
At $10 per column, each spin has $20 in action. Over 100 spins on a single-zero wheel:
[ Expected\ Loss=100\times$20\times\frac{1}{37}\approx$54.05 ]
The same 100 spins on a double-zero wheel have an expected loss of about $105.26.
Betting all three columns
Covering every column uses three equal units. Any result from 1 through 36 makes one column win 2 units while the other two lose one unit each. Net result: zero.
If a zero pocket appears, all three wagers lose.
On single-zero roulette:
- 36 pockets: net 0;
- one pocket: net -3 units.
Expected value:
[ EV=\frac{36}{37}(0)+\frac{1}{37}(-3)=-\frac{3}{37} ]
The player has created a system that usually produces no change and occasionally loses three units. The edge remains 2.7027% of the three units wagered. This illustrates the function of zero more clearly than almost any other roulette system.
Columns versus dozens
Columns and dozens both:
- cover 12 numbers;
- pay 2 to 1;
- lose on zero and double zero;
- have the same house edge on the same wheel.
Their only mathematical difference is which numbers are grouped.
A dozen contains a consecutive block: 1–12, 13–24, or 25–36. A column takes every third number through the layout. Historical results may make one grouping look active, but the next spin does not remember the pattern. The dozens-bet odds guide covers that neighboring wager.
La Partage and En Prison usually do not help
La Partage and En Prison normally apply only to even-money bets such as red/black, odd/even, and low/high. A column is a 2-to-1 wager, so it does not normally receive half-loss treatment when zero appears.
Do not transfer the 1.35% La Partage edge from an even-money bet to columns. The column still loses in full on zero unless a specific approved table rule says otherwise.
Table procedure and dispute points
Column bets are visually simple, but several errors recur:
- a chip is placed between a column box and a dozen box;
- late wagers are moved after “no more bets”;
- a player assumes a chip covers two adjacent columns;
- mixed-color cash chips are confused with roulette color chips;
- a winning column is paid 2 units total instead of 2 units profit plus stake;
- a zero result is incorrectly treated under an even-money half-loss rule;
- several players claim the same ambiguous stack.
At a traditional roulette table, use the denomination and chip color assigned by the dealer, place the wager squarely inside the intended column box, and avoid touching chips after betting closes.
For a disputed settlement, record the winning number, wheel type, wager position, chip value, and any special rule displayed at the table. Surveillance can verify timing and placement more reliably when the chip is not straddling a line.
A better way to compare column play
Before making the wager, answer four questions:
- Is the wheel single-, double-, or triple-zero?
- How much total action will be placed each spin?
- Is one column being played, or is a two-column system doubling exposure?
- How many spins are planned?
Then calculate:
[ Expected\ Loss=Total\ Action\times House\ Edge ]
A column bet is easy to understand and produces a middle level of hit frequency and payout. It is not a strategy for identifying a favorable part of the wheel. The three columns are balanced by design, while the zero pockets remain outside all of them and collect the mathematical price.