The standard size of a roulette wheel typically measures about 32 inches in diameter for American roulette and slightly smaller for European roulette, which measures around 29 inches. These dimensions allow for a practical spinning size while still accommodating the layout of the wheel and its corresponding betting layout on the table. The wheel contains numbered slots for the various colors and numbers used in the game, with the arrangement designed to create randomness and fairness in gameplay. The size and design of the wheel are integral to the classic casino experience, ensuring visibility for players during the game.