Roulette
Red and black roulette odds
Red and black each cover 18 numbers. The win chance is 48.65% on a European wheel, 47.37% on an American wheel and 46.15% on a triple-zero wheel.
48.65%
Chance of red on European roulette
18 / 37 • Standard payout 1:1
Why it is not 50/50
The green zero pockets sit outside both colors. On a single-zero wheel, a red bet wins on 18 pockets and loses on 19. On double zero it loses on 20. A 1:1 payout does not make the probability exactly one half.
A winning color bet pays 1:1
Under standard settlement, a $10 winning color bet earns $10 profit and returns $20 including the stake. The zero outcome loses the full stake unless a specific half-loss or other rule applies.
Betting on both colors
With $10 on red and $10 on black, a colored outcome returns $20 against $20 staked, so net profit is zero. A zero loses both bets. On a European wheel, the chance of an overall profit is 0%, even though one ticket wins on 36 of 37 pockets.
A streak does not change the next spin
After ten reds, the next fair European spin still has an 18/37 chance of red. The chance of ten specified future reds is (18/37)^10. Those are different questions; use the probability guide for the full distinction.