Under badminton court regulations, what is the maximum width of a court line?

Under badminton court regulations, the maximum width of a court line is 40 millimetres.

Court markings must be clearly visible and form part of the areas they define. The Laws of Badminton specify that lines are 40 millimetres wide, so a shuttle landing on a line is considered inside the relevant court area.

This measurement applies to the lines used for singles and doubles boundaries, service lines, and the centre line. The two formats use different boundary markings, but the permitted line width remains the same.

Line width is separate from court dimensions. A full court is 13.40 metres long, while its doubles width is 6.10 metres and its singles width is 5.18 metres. Confusing the 40-millimetre marking requirement with those metre-based court measurements is a common equipment-and-court rules mistake.