Inside the Technology: How VAR and Semi-Automated Offside Work at the 2026 World Cup
Every tight offside call at this World Cup is decided in under a minute, with an animation beamed to giant screens inside the stadium. That speed is not luck — it is the product of a tracking system built from 29 data points per player, a sensor stitched inside the match ball, and a review room watching every match live. Here is exactly how it works.
The Problem Semi-Automated Offside Technology Was Built to Solve
Before automated tracking, offside decisions relied on an assistant referee sprinting the touchline, watching two moving lines of players from a side angle, and making a judgment call in real time. Broadcast replays later exposed how often the margin was a matter of centimeters — far smaller than the human eye can reliably resolve from 40 meters away. FIFA first trialed Semi-Automated Offside Technology (SAOT) at the 2022 World Cup in Qatar, refined it through the 2023 Women's World Cup and Euro 2024, and has carried the same core system into the 2026 tournament across all 16 host venues.
📡 WHAT THE SYSTEM TRACKS
Twenty-Nine Points, Fifty Times a Second
A dedicated array of tracking cameras, mounted beneath the stadium roof, follows every player on the pitch and logs 29 distinct skeletal points on their body — shoulders, elbows, wrists, hips, knees, ankles, and the head — fifty times every second. That density of data is what lets the system identify the exact moment a teammate's foot, knee, or shoulder plays the ball, and where every potential offside player's furthest-forward body part was positioned at that precise instant. A human assistant referee, by contrast, is working from a single eye-line and a far slower visual update rate.
The limb that matters for offside is whichever part of the body can legally play the ball — so hands and arms are excluded from the calculation, while the kicking foot, torso, or head are not. The system is built specifically to apply that rule consistently, on every player, on every phase of play, without fatigue.
The Ball Itself Is Part of the System
The official match ball used at this World Cup carries a sensor suspended in its core, sampling its position 500 times per second and transmitting that data live to the stadium's tracking system. This is what lets the technology pinpoint the exact millisecond of contact between a passer's foot and the ball — a moment that used to be the single hardest thing for a human assistant referee to judge from distance, especially on a fast, low pass played along the ground.
Combine the ball's contact timestamp with the 29-point skeletal tracking of every player on the pitch at that same instant, and the system can automatically construct the offside line and flag a potential infringement within seconds — long before the on-field assistant referee has even raised a flag.
What Happens in the Video Review Room
None of this is fully automatic in the sense of replacing human judgment entirely. Every flagged offside passes through a dedicated video match official sitting in a centralized review room, who checks the automatically generated calculation against the broadcast footage before it is confirmed. Only once a human official signs off does the decision go to the on-field referee.
🔄 THE REVIEW SEQUENCE
1) Ball-tracking sensor flags the pass moment → 2) Skeletal tracking calculates each player's offside line at that instant → 3) The system generates a candidate offside alert → 4) A video match official manually verifies the calculation against camera footage → 5) The on-field referee is informed and the call stands or is waved off → 6) A 3D animation is rendered for the stadium screens and broadcast.
Why the Animation Takes as Long as It Does
The data itself is calculated almost instantly, but generating the broadcast-ready 3D animation — the camera-angle graphic showing the offside line crossing a player's boot — is a separate rendering step that happens after the decision is already confirmed. That is why fans sometimes see the referee signal a decision several seconds before the animation appears on the big screen; the call was already made using the raw tracking data, and the graphic is being produced afterward purely for transparency.
What the Technology Does Not Decide
SAOT only assists with one specific category of call: whether an attacking player was in an offside position the instant the ball was last played by a teammate. It plays no role in handball, foul, or red-card reviews, which remain entirely the judgment of the video match official reviewing broadcast camera angles in real time, the same VAR process introduced for the 2018 World Cup. The technology narrows the margin for human error on one notoriously close call — it does not remove the referee from the game.