A tennis fault is an unsuccessful serve: the ball does not land in the correct service box, or the server breaks a serving rule. One fault does not cost the point. The server gets a second serve—but a fault on that attempt is a double fault, and the receiver wins the point.
Knowing what counts as a fault helps make sense of calls during a match, from a serve that clips the net to a foot fault at the baseline. Here’s how the rules work and what to watch for.
What counts as a tennis fault?
A serve is a fault if the server fails to put the ball into the correct service court or commits a serving violation. The service court is the box diagonally opposite the server. A ball that lands on one of the box’s boundary lines counts as good.
A serve can be called a fault for several reasons:
- The ball lands outside the correct service box. It may land long, wide, or in the wrong box.
- The ball hits the net and does not land in the correct box. If it lands outside the box—or hits the net and then goes out—the serve is a fault.
- The server commits a foot fault. This happens when the server breaks the rules about where or how their feet may move during the serve.
- The ball touches the server or their partner before it lands in the service court.
- The ball hits a permanent fixture, such as a backstop or ceiling, before it bounces in the correct service court.
For example, if a right-handed player serves from the deuce court, the ball must land in the receiver’s diagonally opposite service box. If it lands in the box beside that one, it’s a fault—even if the serve was fast or difficult to return.
What happens after a fault?
Players get two serves on each point. If the first serve is a fault, the server gets a second serve from the same side of the court. A second fault on that point is called a double fault, and the receiver wins the point.
| Serve attempt | Result |
|---|---|
| First serve is a fault | The server takes a second serve. |
| Second serve is good | The point continues. |
| Second serve is a fault | It is a double fault; the receiver wins the point. |
A fault does not change the score by itself. It matters because it uses up one of the server’s two attempts. That’s why a first-serve fault can make the next serve feel more pressured: the server must now get the ball in or lose the point.
What is a foot fault?
A foot fault is a serving fault caused by the server’s position or foot movement. The server must stand behind the baseline, between the imaginary extensions of the center mark and the sideline. During the serve, they must not:
- Touch the baseline or the court inside it with either foot.
- Step outside the imaginary sideline or center-mark extensions.
- Walk or run while serving, or change position by walking or running.
A player may shift their feet or make small movements, provided they do not break those rules. A foot fault can be hard to spot at full speed, especially when a server’s momentum carries them toward the line. Still, touching the baseline before hitting the ball is enough for a call.
Foot faults can be called in singles and doubles. They count just like any other service fault: on a first serve, the player gets a second attempt; on a second serve, it means a double fault.
Is a serve that hits the net always a fault?
No. If the serve touches the net and then lands in the correct service box, it is usually a let, not a fault. The server repeats that serve, and the let does not count against either attempt. So a let on a first serve means another first serve; a let on a second serve means another second serve.
If the ball clips the net but lands outside the correct box, it is a fault. The key is where the ball lands, not simply whether it touched the net.
A let can also be called if the receiver was not ready and did not try to return the serve. In that case, the serve is replayed.
Fault vs. an out shot during a rally
In tennis, “fault” usually refers to a serve that breaks a serving rule or misses its target. If a player hits a groundstroke during a rally and the ball lands out, players generally call it “out” rather than a service fault. The result is still that the player who hit the ball loses the point.
This distinction matters when following the score. A first-serve fault is not the same as losing a point for hitting a ball long: after the fault, the server still has another serve.
Common examples
- Serve lands long: Fault. The ball missed the service box.
- Serve clips the net and lands in the box: Let. Replay the serve.
- Server touches the baseline before contact: Foot fault.
- First serve is wide, second serve lands in: The point continues; the first fault does not end it.
- Second serve lands wide: Double fault; the receiver wins the point.
Frequently Asked Questions
Does a fault mean the server loses the point?
Not if it is the first fault on that point. The server gets a second serve. A fault on the second serve is a double fault, which gives the receiver the point.
Does a ball that lands on the service-box line count?
Yes. The service-box boundary lines count as part of the box, so a serve landing on one of them is good.
Does a net cord count as a fault?
Not automatically. If the serve touches the net and lands in the correct service box, it is a let and is replayed. If it lands outside the box, it is a fault.
Can a player get a foot fault on a second serve?
Yes. A foot fault counts as a service fault on either attempt. If it happens on the second serve, it is a double fault and the receiver wins the point.
Final Thoughts
A tennis fault is a failed or illegal serve, and the first one gives the server another try. The main things to remember are that the serve must land in the correct diagonal box, the server must obey the foot-position rules, and a net serve that lands in the box is a let. Two faults on the same point add up to a double fault—and a point for the receiver.
