Start with the wheel in front of you
Before you buy in, look at the wheel itself. The colour pattern is not decoration; it is the first thing that tells you which version of the game you are playing. A wheel with a single green pocket marked zero is a European-style wheel. A wheel with two green pockets, one marked zero and one marked double zero, is an American-style wheel. The number of red pockets is the same on both, but the extra green pocket changes the arithmetic of every bet you can make.
There are 18 red pockets and 18 black pockets on every standard roulette wheel. The numbers are arranged so that red and black alternate around the wheel, and the sequence is fixed for each wheel type. The green pockets are the house's edge made visible: they are neither red nor black, so any bet on red, black, odd, even, high or low loses when the ball lands in a green pocket.
Where the red numbers sit
The red numbers on a European wheel are: 1, 3, 5, 7, 9, 12, 14, 16, 18, 19, 21, 23, 25, 27, 30, 32, 34 and 36. The black numbers are the remaining non-zero numbers. The single zero is green. On an American wheel the same 18 numbers are red and the same 18 are black, but the wheel also carries a green double zero next to the single zero.
This matters because the colour of a number is not random and not optional. A player who bets on red is betting on exactly 18 of the 37 or 38 pockets, and the payout is even money. The green pocket is the reason that even-money bet does not pay at true odds. On a European wheel, red wins on 18 of 37 pockets, so the chance of winning a red bet is 18/37, not 18/36. The missing fraction is the house edge.
| Wheel type | Red pockets | Black pockets | Green pockets | Total pockets |
|---|---|---|---|---|
| European | 18 | 18 | 1 | 37 |
| American | 18 | 18 | 2 | 38 |
The table above is the whole colour story. The practical difference is that the American wheel's second green pocket makes every bet on red or black lose slightly more often than the same bet on a European wheel. The colour of the pockets does not change; the number of pockets that are neither red nor black does.
How a round runs
A roulette round moves faster than most new players expect. You buy in at the table, the dealer exchanges your cash for coloured chips that are yours alone for that session, and you place bets on the layout before the dealer calls for no more bets. The ball is spun in the opposite direction to the wheel, and when it drops into a pocket the dealer marks the winning number and settles bets.
The sequence matters because every decision you make happens before the spin. Once the dealer calls no more bets, nothing on the layout can be changed. New players sometimes reach for a chip as the ball is slowing, and the dealer will stop them. The bet stands or it does not exist; there is no in-between state.
At settlement, winning bets are paid and losing bets are cleared from the layout. If you bet on red and the winning number is red, you receive even money on that bet. If the winning number is green, the red bet loses, along with black, odd, even, high and low. This is the single most common moment of confusion for a first-time player: an even-money bet that loses not because the opposite colour won, but because neither colour won.
What each bet type costs you
Roulette offers many bets, and they do not all carry the same expected loss. The colour bet is only one option. Inside bets on single numbers pay more but win less often; outside bets on red, black, odd, even, high or low pay even money and win close to half the time. The house edge on most roulette bets is the same on a given wheel, because the edge comes from the green pocket rather than from the payout structure of any particular bet. The exception is the American five-number bet on 0, 00, 1, 2 and 3, which carries a higher edge than the rest of the layout.
| Bet | Pays | European wheel edge | American wheel edge |
|---|---|---|---|
| Red or black | Even money | Same as the wheel's standard edge | Same as the wheel's standard edge |
| Odd or even | Even money | Same as the wheel's standard edge | Same as the wheel's standard edge |
| Single number | 35 to 1 | Same as the wheel's standard edge | Same as the wheel's standard edge |
| Five-number (0, 00, 1, 2, 3) | 6 to 1 | Not available | Higher than the wheel's standard edge |
The exact percentages are printed in the game information panel of the online table you are playing, and a live dealer will tell you the table minimums and maximums before you sit down. What the table above shows is the structure: the wheel type sets the baseline, and one American bet is worse than the rest.
Buy-in, chips and the mistakes that cost time
At a live table you buy in with cash, and the dealer gives you roulette chips that have no value printed on them. Their value is set by your buy-in divided by the number of chips you receive, and the dealer marks that value on the table. These chips are not interchangeable with the cash-value chips used at other table games, and you cannot cash them at the cage. You must exchange them back at the roulette table before you leave.
Three procedural mistakes repeat with new players. The first is placing a bet after the dealer has closed betting, which voids or returns the bet and slows the table. The second is stacking chips from two different players on the same spot, which creates a dispute about who owns the winning bet; the dealer issues different coloured chips precisely to prevent this. The third is leaving the table with roulette chips still in hand, because they are worthless at the cage and at every other table.
Online roulette removes the chip-handling layer but keeps the decision sequence. You select a chip value, click the layout to place bets, and the spin resolves automatically. The same rule applies: once the spin starts, the bet is fixed. The colour count is identical online and on a physical wheel, because the software models the same 37 or 38 pockets.
Why the colour count is only the beginning
Knowing there are 18 red pockets answers the question, but the useful knowledge is what the other 19 or 20 pockets do to your bet. A red bet is not a coin flip, and the gap between a coin flip and a red bet is exactly the green pocket. On a European wheel that gap is one pocket in 37; on an American wheel it is two in 38. The difference is small in any single spin and persistent over thousands of them.
Roulette is a negative-expectation game on every bet, and no pattern of red and black bets changes that. The wheel has no memory, and a run of reds does not make black more likely on the next spin. What a player controls is which wheel they sit at, which bets they place, how long they play, and how much they stake per spin. The colour count is fixed; those four choices are not.
FAQ
Does an American wheel have more red numbers than a European wheel?
No. Both wheels have 18 red and 18 black numbers. The American wheel adds a second green pocket, the double zero, which means the same red bet loses slightly more often on an American wheel than on a European one.
What happens to a red bet when the ball lands on zero?
The red bet loses. The zero pockets are green, not red or black, so any bet on red, black, odd, even, high or low loses when the ball lands in a green pocket. Some European tables offer a rule that returns part of an even-money bet when zero lands, but that rule is table-specific and printed in the table's terms.
Can I bet on red and black at the same time to cover most outcomes?
You can place both bets, but the combined position still loses when the ball lands in a green pocket, and when it lands on red the black bet loses and the red bet pays even money, leaving the two bets to cancel out. The position does not remove the house edge; it just redistributes which spins produce a loss.
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This article is general information about how these mechanics work. It is not legal advice and not a recommendation to gamble or to use any particular operator. Availability and legality differ by jurisdiction — check the rules that apply where you are.