According to badminton court regulations, a singles court is 5.18 metres wide.
The singles sidelines are the inner pair of long boundary lines on a full badminton court. Doubles uses the wider outer sidelines, making the doubles court 6.10 metres wide. Both formats share the same court length of 13.40 metres.
The narrower singles court reflects the fact that one player must cover the playing area alone. A common mix-up is confusing the singles width with the doubles width or with the short service line, which is a separate marking. Court dimensions are laid out in the Laws of Badminton and are used for international competition.