Expected Goals (xG) is a statistical metric that assigns a probability between 0 and 1 to each shot in football, representing how likely an average professional player is to score from that exact chance. A penalty kick has an xG of approximately 0.76. A header from 25 metres has an xG of roughly 0.02. The metric was developed from large databases of historical shots, quantifying which shot locations and contexts produce goals most reliably.

xG is calculated from several factors: shot location (distance and angle from goal), body part used (foot, header, or weaker foot), whether the chance was created by a key pass, whether it came from a counter-attack, goalkeeper positioning, and defensive pressure. Each factor is weighted based on its historical correlation with goal conversion.

In modern football analysis, xG is used for three purposes: team-level xG per match measures whether a team is creating and conceding quality chances; player-level xG vs actual goals measures finishing efficiency; and shot maps reveal tactical patterns in attack and defence.