how many points are needed to win a game of badminton?

To win a game of badminton, a player (or pair) must reach 21 points and be at least two points ahead. If the score reaches 20-20, the game continues until one side has a two-point lead, up to a maximum of 30 points; the first to reach 30 wins the game. In most competitive formats, matches are best of three games, so a player must win two games to win the match. [web results, consistent with standard badminton rules]