xG Guide · Reference

xG glossary

Every term in the expected goals family, in plain words. Where a term has more than one meaning on different sites, both are given.

The basics

xG (expected goals): The chance a shot becomes a goal, from 0 to 1, judged from similar past shots. A team's xG adds up its shots. More →
Shot quality (xG per shot): A team's or player's xG divided by its shots: are the chances good or hopeful?
xGA (xG against): The xG a team concedes: the quality of the chances it allows.
xGD (xG difference): xG for minus xG against. Not to be confused with the xG Gap.
xG Gap: Xgoals' name for xG minus goals: how far a score is behind (+) or ahead (−) of its chances. More →
xG per 90: xG scaled to 90 minutes, so players with different playing time can be compared.
npxG: Non-penalty xG: xG without penalties. Set pieces stay in. More →

After the shot

xGOT / PSxG: Expected goals on target (Opta) and post-shot xG (FBref): the value of a shot on target from where it was placed. Off-target shots count zero. More →
Goals prevented: A goalkeeper's xGOT faced minus goals conceded: above 0, the keeper saved more than an average one would.
Finishing (goals − xG): Goals scored minus xG. It barely repeats from season to season. More →

Before the shot

xA (expected assists): Two meanings: Opta values each completed pass by its chance of becoming an assist; FBref's xAG and others give the passer the xG of the shot that followed.
Key pass: A pass followed by a shot that is not scored.
Big chance: An analyst's tag for a chance a player should reasonably score; a judgement, not a model output. More →
xGChain: Credits the xG of every possession that ended in a shot to each player involved in it.
xGBuildup: Like xGChain, but without the shooter and the key passer: the work further back.
xT (expected threat): Values zones of the pitch by how likely a goal follows from there; an action earns the change in value it creates.
OBV and VAEP: Models that value every on-ball action by how it changes the chances of scoring and conceding.

Over a match and a season

xPts (expected points): The points a team would collect on average from its chances: 3 × chance of winning + chance of a draw, from simulating the match's shots.
xG race chart: A step chart of each team's xG adding up minute by minute, with goals marked. More →
Shot map: Every shot drawn where it was taken, the circle's size its xG, filled when it was a goal.
Live xG: xG built during the match from live data: provisional and revised later. More →
Current xG: On Xgoals: a team's xG since its last restart (a goal, half time, a penalty). Live's alerts come from it.

Context

PPDA: Passes allowed per defensive action: lower means more pressing. Confused by where on the pitch a team plays.
Field tilt: A team's share of play in the final third. Sources define it differently.
Game state: The score at a moment; leading teams shoot less, but better, which most xG models ignore.

How models are judged

Calibration: Whether shots given 0.20 really go in about 20% of the time. The key test of an xG model.
Brier score: A measure of a probability model's error; good xG models score about 0.08. Lower is better.
Freeze frame: The position of every visible player at the moment of a shot, as recorded by StatsBomb. More →
Event data: Match events (passes, shots, tackles) notated by trained operators, the raw material of xG. More →

Questions

What is the difference between xG and xGOT?

xG values the chance before the shot; xGOT values a shot on target from where it was placed. A great strike from a poor chance has low xG and high xGOT.

What is npxG?

Non-penalty xG: xG without penalties, so a team or player is not flattered by spot kicks. Corners and free kicks stay in.

Sources

Checked 2026-10-28. Methods change: every figure here is dated to its source.

xG explains football; it is not a betting tip. 18+ · Please gamble responsibly.