A full badminton court is 13.4 metres long from one back boundary line to the other.
That length applies to both singles and doubles play. The principal difference between the two formats is court width: singles uses the inner side lines, while doubles uses the outer side lines. The court is divided into two halves by a net placed across its width.
The 13.4-metre measurement is approximately 44 feet. Because the same court length is used for singles and doubles, players in both formats must cover the same front-to-back distance. Doubles generally creates more lateral space because its outer sidelines are in play.
People sometimes confuse court length with the distance between the net and a service line. The short service line is much closer to the net, while the full court extends from one rear boundary to the other. The dimensions are specified in the Laws of Badminton and used in international competition.