What is Expected Goals (xG)?

Expected Goals (xG) is a football metric that estimates how many goals a team or player "should" have scored based on the quality of the chances they created, with each shot assigned a value between 0 and 1 representing its probability of being scored. That probability is derived from historical data on similar attempts, weighing factors such as distance from goal, angle, body part used, assist type and whether the shot followed a defensive error or a set piece. A shot from the penalty spot carries an xG of roughly 0.76, because historically about 76% of penalties are converted, while a speculative effort from 30 yards might be worth only 0.03. Summing every chance in a match gives a team's total xG, a cleaner signal of performance than the scoreline alone, since actual goals are noisy over small samples. Worked example: a team creates five chances worth 0.10, 0.20, 0.15, 0.35 and 0.76 xG, totalling 1.56 expected goals, yet scores just once. Over one match that undershoot is normal variance, but a side that consistently outscores its xG may be riding unsustainable finishing that regresses. For bettors, xG models feed odds compilers and can flag value: if a team is winning results while being outperformed on xG, the market may overprice them, and a contrarian back against them can carry positive expected value. The common mistake is treating a single match's xG as decisive rather than a large sample. Compare with expected value, Poisson distribution and both teams to score.