A tennis court can look deceptively simple from the stands, but a few feet make a big difference: they create the doubles alleys, set the service boxes, and give players room to chase a wide ball. If you’re laying out a court, checking a facility, or just trying to picture the dimensions, the key numbers are straightforward: a regulation court is 78 feet long, and it is either 27 feet wide for singles or 36 feet wide for doubles.
Regulation tennis court dimensions
| Measurement | Dimension | What it describes |
|---|---|---|
| Court length | 78 feet | Baseline to baseline |
| Singles court width | 27 feet | Between the singles sidelines |
| Doubles court width | 36 feet | Between the doubles sidelines |
| Doubles alley width | 4.5 feet per side | Space between a singles and doubles sideline |
| Net height at center | 3 feet | Measured from the court surface |
| Net height at posts | 3.5 feet | Measured where the net meets its supports |
The length stays the same for singles and doubles. Doubles adds 4.5 feet of width on each side, making its playing area 9 feet wider overall. The lines count as part of the area they mark: a ball touching a boundary line is in.
How the court is laid out
The net divides the 78-foot length into two equal halves, so each baseline is 39 feet from the net. The service lines sit closer to the net: each is 21 feet away from it, or 18 feet inside the baseline. That leaves a 21-foot-deep service area on each side of the net.
A center service line splits each service area into two boxes. Since the singles court is 27 feet wide, each service box is 13.5 feet wide. In other words, each box measures 13.5 feet across by 21 feet deep. The server must send the ball diagonally into the box opposite them.
The center mark is a short line at the midpoint of each baseline. It helps a server line up on the correct side: stand to the right of it when serving into the receiver’s right-hand service box, then switch sides for the next point. It is 4 inches long.
Singles and doubles: where the extra width goes
Singles uses the inner sidelines, 27 feet apart. Doubles uses the outer sidelines, 36 feet apart. The 4.5-foot strips between those pairs of lines are called the doubles alleys. They count as in during a doubles rally, but not during a singles rally.
That difference is easy to spot in a match. A singles player can hit a ball into the alley and win the point if it lands beyond the singles sideline. The same shot would be out in singles if it lands beyond that inner line. In doubles, however, the alley is part of the court, giving teams more room to stretch a rally wide.
When singles is played on a court marked for doubles, the net is still supported at the doubles posts. Singles sticks are placed 3 feet outside each singles sideline to hold the net at the proper height for singles. They raise the net to 3.5 feet at those points; the net remains 3 feet high at the center.
Measurements that matter around the net
The net is 3 feet high at the center and 3 feet 6 inches at the posts or singles sticks. A center strap pulls it down to the required center height. The net posts sit 3 feet outside the doubles sidelines; for singles-only courts, they sit 3 feet outside the singles sidelines. These details help keep the net at the right height across its span.
Line widths also matter when measuring or repainting a court. Most lines are between 1 and 2 inches wide. The baseline can be up to 4 inches wide, giving the server a clear visual reference behind the court. Because a line is in, its width affects the measured playing area rather than sitting outside it.
Court size versus the space needed to build one
The 78-by-36-foot measurement describes the doubles playing rectangle, not the full footprint a court needs. Players need clear space beyond the baselines and outside the sidelines to run, change direction, and reach wide shots safely. A court built exactly to its playing dimensions, with no surrounding clearance, would be cramped and unsuitable for normal play.
For example, a player sprinting back to retrieve a lob needs room beyond the baseline to slow down. A doubles player chasing a shot into the alley needs space beyond the outer sideline. The amount of clearance depends on the facility and its intended use, so check local building guidance and the relevant tennis organization’s specifications before planning construction. Do not treat the painted court dimensions as the total site dimensions.
Quick ways to picture the measurements
- Length: At 78 feet, the court is 26 yards from baseline to baseline.
- Singles width: The 27-foot width is 9 yards between the inner sidelines.
- Doubles width: The full 36-foot width is 12 yards between the outer sidelines.
- Service boxes: Each one is 21 feet deep, a little over half the distance from the net to the baseline.
These comparisons are useful when estimating a layout, but they are not substitutes for a tape measure during construction. Even a modest error in the service-line position can make the court play differently from a regulation court.
Frequently Asked Questions
Is a tennis court 78 feet long for both singles and doubles?
Yes. Regulation court length is 78 feet for both formats. Singles is 27 feet wide, while doubles uses the full 36-foot width.
How wide is a tennis court in feet?
It depends on which sidelines are being used. The singles court is 27 feet wide; the doubles court, including both alleys, is 36 feet wide.
How far is the service line from the net?
The service line is 21 feet from the net on each side. It is 18 feet from the baseline.
Do the court dimensions include space outside the lines?
No. The regulation measurements describe the playing area. Additional clear space around the court is needed for safe movement and depends on the site and facility requirements.
Final Thoughts
For a quick reference, remember 78 feet long, 27 feet wide for singles, and 36 feet wide for doubles. The service line is 21 feet from the net, and the net stands 3 feet high at its center. Those measurements explain the painted court; safe run-off space around it is a separate part of planning, whether you’re building a facility or simply figuring out how much room a court takes up.
