Badminton — BWF Law 1 and Diagram A
The same court has different boundaries for singles, doubles, and service.
A standard badminton court contains several valid lines at once. The outer side lines belong to doubles, the inner side lines belong to singles, and the rear service boundary changes between the two formats. The correct call depends on whether the match is singles or doubles and whether the shuttle is being served or is already in a rally.
Quick ruling: under BWF Laws of Badminton in force 26 April 2025, Version 5.0 (2), the standard court is 13.4 metres long. It is 6.1 metres wide for doubles and 5.18 metres wide for singles. Every 40 mm line forms part of the area it defines, so a shuttle landing on the relevant boundary line is in.
Decision path
Choose the active boundary before making the call
- Identify whether the match is singles, doubles, or a Para badminton class using a modified court.
- Decide whether the disputed landing is the service or part of the rally after the service has been returned.
- Select the active side line and rear line for that format and phase of play.
- Check the shuttle's landing point against that boundary: touching the active line is in; landing wholly beyond it is out.
- For a service-position dispute, judge the server's and receiver's feet separately. They must stand inside the diagonal service courts without touching those boundary lines.
Dimensions at a glance
The BWF Diagram A measurements
- Full length: 13.4 m, divided by the net into two 6.7 m halves.
- Doubles width: 6.1 m, using the outer side lines.
- Singles width: 5.18 m, using the inner side lines.
- Short service line: 1.98 m from the net on each side.
- Doubles long service line: 0.76 m inside each back boundary.
- Line width: 40 mm, with every line included in the area it marks.
The familiar rounded imperial equivalents are 44 ft long, 20 ft wide for doubles, and 17 ft wide for singles. BWF Diagram A uses metric measurements; those are the governing specifications.
Overall court
The length stays the same in singles and doubles
The back boundary lines are 13.4 m apart, and the net divides that length at the midpoint. Singles does not use a shorter court during ordinary rallies: it uses the full length but a narrower width.
BWF Diagram A gives the full-court diagonal as 14.723 m. That measurement is useful when setting out a court because matching diagonals help confirm that the rectangle is square, but it does not create another playing boundary.
Side lines
Singles is long and narrow; doubles is long and wide
The outer side lines make the doubles court 6.1 m wide. The inner side lines make the singles court 5.18 m wide, leaving a 0.46 m strip between the singles and doubles line on each side.
Those strips are often called doubles alleys. A shuttle landing there is out in singles but in during a doubles rally. The painted outer line remains visible in singles, but it is not the active singles boundary.
Short service line
A serve must reach the front of the diagonal service court
The short service line runs parallel to the net, 1.98 m from it on each side. A serve that lands between the net and the receiver's short service line is out because it has not reached the service court.
The line itself belongs to the service court. An otherwise legal serve whose first landing touches the receiver's short service line has reached the required area and is in.
Rear service lines
Singles and doubles use different back limits for service
In singles, the back boundary line is also the long service line. A singles serve may therefore land on or inside the full back boundary.
In doubles, the active long service line sits 0.76 m inside the back boundary. A doubles serve landing beyond that inner line is out even if it lands before the full back boundary. Once the serve has been returned, the full back boundary becomes active for the doubles rally.
Centre line
The centre line creates right and left service courts
From each short service line to the relevant rear service boundary, the centre line divides the serving area into right and left service courts. The server uses the right court when the serving side's score is zero or even and the left court when that score is odd.
The service travels diagonally into the corresponding receiver's court. After the service is returned, the centre and service lines no longer restrict where players may stand or where the shuttle may land; the active singles or doubles outer boundaries control the rally.
Line width and colour
The entire painted line belongs to its area
BWF Law 1 requires court lines 40 mm wide. They must be easily distinguishable and should preferably be white or yellow. In a multi-sport hall, colour helps identify the badminton layout, but the competition must still make clear which markings are in use.
Because the whole line forms part of the area it defines, the outer edge of the active painted line is the practical limit for a landing decision. There is no neutral strip within the line: contact with any part of it is contact with the defined area.
Shuttle versus feet
“The line is in” does not let a player stand on it to serve
For a shuttle landing, BWF Laws 9.1 and 13.3.1 treat the relevant boundary line as part of the court. A serve or rally shot touching that active line is in.
Player position during service uses a different test. Law 9.1.3 requires the server and receiver to stand within diagonally opposite service courts without touching their boundary lines. A foot on the centre line, short service line, side line, or active rear service line is therefore a service fault even though a shuttle landing on the same active line would be in.
Net and posts
The posts stay on the doubles side lines for every match
The posts are placed on the doubles side lines whether singles or doubles is being played. They must be 1.55 m high and remain vertical when the net is strained. The net must be 760 mm deep and at least 6.1 m wide.
The top of the net is 1.55 m above the court over the doubles side lines and 1.524 m at the centre. Moving the posts inward to the singles side lines would not match BWF Law 1, even though singles uses the narrower floor boundaries.
Practical examples
The same landing can change from out to in
- Singles rally: the shuttle lands in a side alley between the inner and outer side lines. It is out.
- Doubles rally: the same side-alley landing is on the playable doubles court. It is in.
- Doubles service: the shuttle lands between the doubles long service line and the back boundary. It is out.
- Doubles rally: after the serve has been returned, a shuttle landing in that rear strip is in.
- Any correct service court: the shuttle touches the active short, side, centre, or rear service boundary. The landing is in, assuming the service was otherwise legal.
Officials
Line judges decide assigned landing lines
Under BWF Law 17, a line judge indicates whether a shuttle landed in or out on the assigned line. The decision is a finding of fact. The umpire may overrule only when satisfied beyond reasonable doubt that the line judge clearly made the wrong call.
If an Instant Review System is operating, it decides a valid line-call challenge under the applicable review procedure. If a line judge is unsighted and neither the umpire nor the review system can decide, Law 14.2.6 provides a let. Review availability changes the procedure, not which line is active or whether the line counts as in.
Variations
Para badminton can use different court areas
The dimensions above describe the standard court in BWF Diagram A. Wheelchair Badminton uses the court and service areas shown in Diagrams D and E. Standing class SL3 plays singles on the half-court layout in Diagram F; the other standing classes use the standard Diagram A court for singles and doubles.
Youth, recreational, and local formats may also mark or use a reduced area, but that is a competition variation rather than the standard BWF court. Surrounding run-off, ceiling height, flooring, and event presentation requirements are facility matters and should be checked in the regulations for the particular competition.
Common mistakes
Misunderstandings to avoid
- “Singles uses a shorter court” is wrong for standard play. Singles is narrower, but its rally court runs to the full back boundary.
- “Doubles uses every outer line on the serve” is wrong. The wider side lines apply, but the inner doubles long service line is the rear limit.
- “The back doubles service line applies all rally” is wrong. After a legal return, doubles uses the full back boundary.
- “A line touch is out” reverses the BWF rule. The relevant painted line belongs to the area it defines.
- “Players may stand on a service line because the line is in” confuses a shuttle-landing rule with the separate service-position restriction.
Official references
Source material