Badminton service court helper: who serves next in doubles and singles

The rule in one line

The serving side's own score picks the service court:

• Right service court when the server's score is even (0, 2, 4 and so on). 0 counts as even, so every game starts from the right.
• Left service court when the server's score is odd (1, 3, 5 and so on).
• The serve goes diagonally, so the receiver always stands in the service court diagonally opposite: their own right court when the server's score is even, their left when it is odd.

It is the serving side's score that counts, never the total and never the receiver's. A server trailing 6-9 has 6, an even number, and serves from the right. The score is called with the server's score first, so that serve is called "6-9".

Singles: your own score picks the court

In singles both players serve from, and receive in, their right service courts when the server's score is even, and their left service courts when it is odd (Law 10). Win a rally on your own serve and you score and serve again from the other court. Win a rally on your opponent's serve and you score and take over the serve, from whichever court your new score says.

Why each serve comes from that court:

• Start. We serve first. 0 is even: right court.
• Rally 1. We won on serve: 1 is odd, so we serve again from the left.
• Rally 2. They win the serve with 1, odd: left court.
• Rally 3. They won on serve: 2 is even, right court.
• Rally 4. They won on serve: 3 is odd, left court.
• Rally 5. We win the serve back with 2, even: right court, even though we trail 2-3.
• Rally 6. We won on serve: 3 is odd, left court.
• Rally 7. They win the serve back with 4, even: right court.

Doubles: who serves, who receives, who switches

Doubles adds one question: which of the two partners serves. The Laws of Badminton answer it without anyone having to remember who served last (Law 11):

1. The score picks the court. The serving side serves from its right service court when its score is even and its left when it is odd.
2. Win a rally on your own serve: swap. Your side scores, the server and partner swap service courts, and the same player serves again from the other court.
3. Win the serve back: nobody moves. The receiving side scores and becomes the serving side, but neither pair changes courts. Whoever is already standing in the court that matches the new score serves.
4. The receiver is the player diagonally opposite. The receiving side never switches while it is receiving, and only the receiver may return the serve.

Partners switch service courts only after winning a point on their own serve. When the receiving side wins a rally it becomes the serving side without switching, and the partner standing in the court that matches its score serves.

The Law 11 example, rally by rally

This follows the example the Laws of Badminton give for doubles: A and B play C and D, A and B serve first, and A serves from the right service court to C. So A is the first server and C the first receiver; B and D start in their left courts.

Why each rally goes that way:

• Start. A serves first, from the right court because 0 is even, to C diagonally opposite. B and D start in their left courts.
• Rally 1. A and B scored on their own serve, so A and B swap courts and A serves again, now from the left, to D. C and D stay put.
• Rally 2. C and D win the serve. Nobody moves. Their score, 1, is odd, so D, standing in the left court, serves to A.
• Rally 3. A and B win the serve back. Nobody moves. Their score, 2, is even, so B, standing in the right court, serves to C.
• Rally 4. C and D win the serve back. Nobody moves. 2 is even, so C, in the right court, serves to B.
• Rally 5. C and D scored on their own serve, so C and D swap courts and C serves again, now from the left, to A. A and B stay put.
• Rally 6. A and B win the serve back. Nobody moves. 3 is odd, so A, in the left court, serves to C.
• Rally 7. A and B scored on their own serve, so they swap and A serves again, now from the right, to D.

The serving order that falls out of it

Read down the "Next serve" column and the serve passes from A to D to B to C and back to A. That is the sequence Law 11.4 sets out: from the first server, to the partner of the first receiver, to the partner of the first server, to the first receiver, then round again. However many points each serve lasts, the order never changes within a game, which is a quick way to check you are standing in the right place.

Starting a new game

• The winner of the previous game serves first in the next game (Law 7.6), from the right service court, because the score is back to 0.
• In doubles, either player of the side that won the game may serve first, and either player of the other side may receive first (Law 11.6). The helper lets you pick both again at the start of every game.
• For the first game, the side that wins the toss chooses to serve or receive first, or picks an end, and the other side takes the remaining choice.
• Players change ends after game 1, and after game 2 if there is a third game. Changing ends never changes which court is "right": right and left are always as each player faces the net.

Game length, 20-all and the cap

The helper follows the game score too, so it knows when a game ends, when the interval comes and when the deciding game needs a change of ends. Both BWF formats are built in:

The service court rule is the same in both: the court still follows the serving side's score. More on the new format in 3x15 scoring explained, and on long games in 20-all and the 30-point cap.

Edge cases

• 0 is even. Every game starts from the right court, and so does every serve at 2, 4, 6 and so on.
• Forgot to change ends? Change as soon as someone notices, while the shuttle is not in play. The score stands (Law 8).
• Wrong court, wrong server or wrong receiver? That is a service court error: put it right as soon as it is noticed, and the score stands (Law 12).
• A let changes nothing. The rally is replayed with the score unchanged, so nobody moves and the same player serves again from the same court.
• No second serve. A service fault loses the rally: the receiving side scores and takes the serve, and nobody changes court.
• After the serve, anyone can hit. Positions only matter at the serve. Once the serve is returned, either player on a side may hit the shuttle from anywhere on their side of the net.
• 29-all (20-all in 3x15). The next rally wins the game, 30-29 (21-20). The court rule still applies to that last serve.