How Does Electronic Line Calling Work in Tennis? Live Calls vs Video Review

Electronic line calling in tennis uses technology to decide whether a ball lands inside or outside the court. With a live system, an automated call arrives during the point, rather than waiting for a player to challenge a human line judge’s decision.

It helps explain why modern matches can have fewer officials beside the court while still keeping a chair umpire. But line calling and video review solve different problems. Understanding that distinction makes close points much easier to follow.

How does electronic line calling work?

Camera-based systems track the ball and use software to establish its landing position relative to the court lines. The system turns that result into a call. The number and arrangement of cameras depend on the technology and installation, so a single camera count should not be treated as universal.

A ball touching the relevant line is in. The question is where it lands, rather than where it appears to be in a television image. A low camera angle or a player’s position can make a close bounce difficult for viewers to judge.

Live calls and player challenges are different

In a review-based arrangement, people make the initial call and technology checks a disputed landing. With live electronic line calling, the system makes the initial line decision.

The ATP announced adoption of live electronic line calling across its Tour from 2025. That does not mean every tennis competition worldwide uses an identical setup: tournaments, tours and competition levels have their own arrangements.

Why is there still a chair umpire?

A line decision is only one part of officiating. Officials also deal with scoring, conduct and incidents that concern how the point was played. A disputed second bounce, for example, is a different question from whether the ball landed beyond a line.

Think of two hypothetical points. In the first, a shot lands near the sideline: line-calling technology addresses the landing. In the second, the ball bounces twice before a player hits it: the issue concerns the sequence of play. The same replay graphic cannot be assumed to answer both questions.

How is video review different?

Video review allows officials to inspect footage of certain disputed incidents. In March 2026, Wimbledon announced video review for six show courts, separate from the electronic line-calling system.

When a player asks for a review, listen to what they are disputing. A discussion about a touch, double bounce or other incident may concern a judgment call rather than the accuracy of an out call.

Who checks the technology?

The International Tennis Federation introduced Gold, Silver and Bronze classifications in July 2025. These cover different competition levels. Its assessment principles include accuracy, reliability, suitability and practicality, with ongoing monitoring also part of the approach.

That is a useful reminder that automated does not mean exempt from evaluation. Fans can ask whether a system is approved for its intended use without assuming either that every close decision is wrong or that equipment can never fail.

What to watch during the next match

• Listen for an automated out or fault call.
• Distinguish a line dispute from a dispute about how the point unfolded.
• Check the tournament’s review arrangements before assuming a player has the same options as at another event.
• Use replays as context, while remembering that ordinary broadcast footage may not reproduce the line-calling system’s evidence.

For match coverage alongside the rules, browse NOWLIVO’s Tennis section. Knowing which decision the technology is making is often more useful than simply asking whether tennis has replaced its line judges.