The service boxes are the four rectangles near the net that decide whether a serve lands in or out. Knowing where they begin and end makes it easier to judge calls, return serves, and practise placement with purpose.
Each serve must land in the service box diagonally opposite the server. The lines around that box count as part of it, so a ball clipping the service line or sideline is good. Here’s how to spot the boxes and use them to understand the rules and tactics of a tennis court.
What Are the Tennis Court Service Boxes?
Service boxes are the two marked areas on each side of the net. A center service line divides each side into a left box and a right box. Together, the four boxes form the target areas for serves.
A service box is bordered by the net, the service line, the center service line, and the singles sideline. The doubles alley—the extra strip along each side of a doubles court—is not part of the service box.
| Part of the court | Standard measurement |
|---|---|
| Net to service line | 21 feet (6.4 metres) |
| Width of one service box | 13.5 feet (4.1 metres) |
| Length of one service box | 21 feet (6.4 metres) |
| Baseline to net | 39 feet (11.9 metres) |
These measurements are the same on standard singles and doubles courts. The court’s doubles sidelines sit farther out, but serves still have to land inside the narrower singles sidelines.
How the Service Boxes Work
A player serves from behind the baseline, starting on one side of the center mark or the other. The first serve of a game is hit from the right half of the court, often called the deuce court. It must land in the receiver’s right-hand service box, which is diagonally opposite.
After that point, the server alternates sides after each point. A serve from the left, or ad court, must land in the receiver’s left-hand box. The server keeps alternating until the game ends. The same pattern applies in singles and doubles.
If a serve lands outside the correct box, it is a fault. A second fault on the same point is a double fault, and the receiver wins the point. If the ball touches the net and then lands in the correct service box, it is a let and the serve is replayed. A serve that touches the net but lands outside the box is still a fault.
Which Lines Count as Part of the Box?
Any boundary line around the correct service box counts as in. That includes the service line, the center service line, and the singles sideline. If even part of the ball touches one of those lines after landing, the serve is good.
The baseline and the net are not the far and near edges of the service box. A serve that lands short of the net or beyond the service line is not a legal serve. In practical terms, the ball has to clear the net and bounce between the net and service line, within the correct side boundaries.
Finding the Service Boxes on a Court
Start at the net and look for the line running parallel to it, about 21 feet away. That is the service line. The short line running from the net toward the service line is the center service line. It divides the area between net and service line into two boxes.
On a doubles court, ignore the outer doubles sidelines when judging a serve. The service box ends at the singles sideline, the inner boundary line. This is a common source of confusion for new players because the full court looks wider during doubles rallies than it does during the serve.
Why Service-Box Placement Matters
A serve does not need to be fast to be effective. Aiming for a particular part of the box can pull the returner out wide, jam them near the body, or set up the next shot. For example, a right-handed server on the deuce side might use a slice serve toward the receiver’s backhand, sending the ball toward the outer edge of the box. A serve closer to the center line can instead crowd the returner and limit their angle.
Placement is useful for recreational players, too. Rather than trying to hit the line, aim for a safe target with room to spare. If you’re practising, divide the service box into wide, body, and center targets. Hitting those areas reliably is often more valuable than swinging harder and collecting faults.
Remember that the target changes with the server’s position. From the deuce side, the server aims crosscourt into the receiver’s deuce box; from the ad side, the target is the receiver’s ad box. Thinking “diagonal” before each serve helps prevent the common mistake of aiming into the box directly across the net.
Common Service-Box Mistakes
- Aiming straight ahead: The serve must land diagonally across the net, not in the box directly opposite the server.
- Counting the doubles alley: The alley is out for a serve, even during a doubles match.
- Calling a line serve out: The lines that border the correct service box are in.
- Serving from the wrong side: Start each game on the deuce side, then alternate sides after every point.
- Stepping over the baseline early: The server must stay behind the baseline until the racket makes contact with the ball.
Frequently Asked Questions
How big is a tennis service box?
Each standard service box is 21 feet long and 13.5 feet wide. It runs from the net to the service line and from the center service line to the singles sideline.
Does the doubles alley count as part of the service box?
No. The doubles alley is out when serving. A serve must land between the center service line and the singles sideline, even in a doubles match.
Is a serve that lands on the service line in?
Yes. The service line is part of the service box, so a serve that touches it is good as long as it lands in the correct diagonal box.
Can a serve hit the net and still be good?
Yes. If it touches the net and lands in the correct service box, it is a let and the server replays that serve. If it lands outside the box, it is a fault.
Final Thoughts
The service boxes are simple targets, but they shape every point that begins with a serve. Remember the key details: aim diagonally, keep the serve inside the singles sidelines, and treat the boundary lines as in. Once you can read the boxes at a glance, calling serves and choosing smarter targets become much easier.
