Tennis has some very visible rules—like staying within the lines and not touching the net—but others are less obvious. One that tends to confuse newer players and frustrate professionals alike is the foot fault.
It’s not always easy to spot, but it’s one of the most strictly enforced rules during the serve. Here’s what a foot fault actually is, how it’s called, and why it matters.
A foot fault occurs when a server violates the rules of positioning or movement with their feet during the service motion.
This includes:
The rule is in place to make sure the server doesn’t gain an unfair advantage by creeping closer to the net or shifting their position illegally before the ball is struck.
The key moment is the instant the racket makes contact with the ball. If the server’s feet are not within legal boundaries at that moment, it’s a foot fault.
At the professional level, line judges or chair umpires are responsible for calling foot faults. They closely watch the server’s feet during every serve. In some tournaments, especially higher-tier events, electronic line calling systems also track foot positioning in real time.
If a foot fault is called, the serve is considered a fault, just like if the ball went into the net or landed outside the service box. On a second serve, a foot fault results in a double fault, and the server loses the point.
In recreational or club tennis, it’s often self-policed or called by an opponent. This can sometimes lead to disputes, especially since many casual players don’t have officials watching the lines.
Even though it might seem minor, foot placement can have a significant impact. Leaning into the court early can cut down the distance between the server and receiver, giving the server a timing and angle advantage.
In doubles, stepping across the center mark can also disrupt proper court coverage or even obscure the receiver’s line of sight.
Foot faults are meant to ensure the serve starts from a fair, legal position every time—keeping the game consistent and competitive.
Foot faults aren’t always intentional. In fact, many happen because of habit or poor footwork rather than trying to cheat the line. Common reasons include:
Players who struggle with balance or serve mechanics are more likely to foot fault, especially under pressure.
Experienced players develop routines to avoid foot faults. This includes consistent placement of the back foot, making sure the front foot isn’t too close to the baseline, and practicing deliberate, repeatable motions during their serve.
Many will also glance down quickly during their serve setup to check foot positioning—especially on second serves when the risk of a double fault is higher.
At the pro level, players often review footage or receive feedback from coaches to correct foot fault tendencies before they become a problem in matches.
A foot fault in tennis may seem like a small technicality, but it plays an important role in keeping serves fair and legal. It’s one of those rules that’s easy to overlook—until it costs a player a crucial point.
Whether you’re just learning the game or watching high-level competition, knowing how and when a foot fault is called helps you understand a big part of how the serve—and the match—is governed.
