Expected goals, or xG, estimates the probability that a shot becomes a goal. Each shot receives a value between zero and one. This is a model’s probability estimate, not a goal awarded on the pitch.
What does the model consider?
Hudl Statsbomb lists distance, angle, body part and the action creating the chance among common inputs. Models use information from similar historical shots; some also include the goalkeeper and surrounding players.
Different inputs and modelling choices can produce different values for the same shot. A discrepancy does not automatically make one website wrong.
Adding shots together
Imagine three shots assigned 0.10, 0.25 and 0.40 xG. Their total is 0.75. These numbers are invented to demonstrate addition, not taken from a real player or match.
A total can exceed one because it combines multiple shots. A total of 0.75 does not mean three-quarters of an actual goal, nor does it automatically mean a 75% chance of winning.
Why do goals differ from xG?
A shot either scores or does not. Low-probability chances can go in, and high-probability ones can be missed. One match’s gap between goals and xG is therefore insufficient to establish a player’s finishing ability.
Compare like with like
Check the provider, period, whether the figure covers a match or season, and whether penalties are included. Prefer the same model and scope when comparing.
Use xG to ask questions about chance quality alongside the actual score and match events. It does not replace the result, represent win probability or guarantee a correct prediction.