How does 21-point scoring work?

This is the scoring in the 2025 BWF Laws, which apply until 3 January 2027 and which local leagues may keep using after that:

• A match is the best of three games, unless otherwise arranged.
• Every rally scores a point, whoever served.
• A game is won by the first side to 21 points.
• At 20-all, the side that first gains a two-point lead wins the game.
• At 29-all, the side that scores the 30th point wins the game.
• The winner of a game serves first in the next game.

Intervals and changes of ends in the third game come at 11 points.