What Is Hawk-Eye in Tennis? How Electronic Line Calling Works

TL;DR

Hawk-Eye is a camera-based tracking system used to estimate where a tennis ball landed. It helps officials review close line calls, while the tournament’s regulations decide whether it is a challenge tool or the primary electronic line-calling system.

How Hawk-Eye tracks a ball

Synchronized cameras capture the ball from different angles. Software combines those views to model the ball’s flight and estimate the point where it contacted the court. The output is a visualization and decision aid, not a literal camera placed on the line.

Challenge system versus automatic calls

Some events let a player request a review after an official call. Other tournaments use live electronic line calling, with the system announcing calls automatically. The number of challenges, review timing and appeal process are event-specific.

Accuracy and limits

Tracking is an estimate with a margin of error, and the quality depends on camera placement, calibration and court conditions. The official rules remain the authority when a review is unavailable or a technology failure occurs.

Related reading

See what is a tiebreak in tennis and fault vs double fault for the rules situations players most often ask about. You can also compare how tennis scoring works, why players change ends and padel versus tennis.

Reviewed September 29, 2026.