Expected goals, usually written xG, is a number between 0 and 1 assigned to every shot, representing how often a shot from that position, with that body part, in that situation, would be expected to become a goal. A penalty is typically worth about 0.76 to 0.79 xG, because roughly three in four penalties are scored. A speculative shot from 30 yards might be worth 0.03 xG, meaning it would be scored about three times in a hundred. A tap-in from two yards out might be worth 0.90 or more. Add up the xG of every shot in a match and you get each team's total xG, which is a summary of the quality of chances created, not just the number of shots taken.

The reason xG caught on is that raw shot counts mislead. A team that takes 20 long-range shots may have created less danger than a team that takes five clear chances, but a shots table makes the first team look dominant. xG fixes that by weighting each shot by its quality, so the team that created the better chances usually comes out on top even if it shot less often. That is why analysts quote xG alongside the scoreline: the score tells you what happened, and xG tells you what usually happens from chances like those, which is often a better guide to how the game really went.

Read xG as a pair of numbers, one per team, and compare them with the actual score. If a match finished 1-0 but the xG was 2.4 to 0.5 in favour of the losing team, the winner was probably fortunate and the loser probably deserved more. If a match finished 3-0 with xG of 3.1 to 0.4, the result was a fair reflection of the chances. Neither reading guarantees anything about the next match, but over a run of games the pattern is informative: teams that consistently out-create their opponents on xG tend to climb the table, while teams that consistently concede big xG tend to fall, even if results lag behind for a few weeks.

Two cautions matter. First, xG does not measure everything: it rates shots, not the build-up that failed to produce a shot, and it does not fully capture defensive organisation, goalkeeping brilliance or the value of a player who creates space without touching the ball. Second, different providers calculate xG slightly differently, using different models and different definitions, so a team's xG can vary between sources. Compare xG within one provider rather than mixing sources, and treat small differences, such as 1.4 versus 1.6, as noise rather than a meaningful gap.

For team form, xG difference, meaning xG created minus xG conceded, is more stable than points over short runs. A team on a winning streak with a negative xG difference is often riding luck, late goals or outstanding goalkeeping, and its form may cool. A team on a losing run with a positive xG difference is often creating enough to turn things around, provided its finishing or goalkeeping regresses toward normal. Neither pattern is a prediction on its own, but both are better starting points than raw results, which are heavily influenced by a handful of moments in each game.

For players, xG helps separate finishers from chance-getters. A striker who scores 15 goals from 10 xG is finishing brilliantly, or is on a hot streak that may cool. A striker who scores 5 goals from 12 xG is getting into great positions and finishing badly, or is simply unlucky, and may be due a run of goals. The same logic applies to creators: expected assists, or xA, rates the quality of chances a player creates for teammates. Used together, xG and xA give a fairer picture of attacking contribution than goals and assists alone, which reward the final touch rather than the whole move.

The most common misuse of xG is treating it as a prediction machine. An xG total describes the chances in a match that already happened; it does not say the same chances will occur again, because opponents, lineups, tactics and even weather change. Another misuse is quoting xG to claim a team was robbed, when the model never claimed the better xG team deserved to win: football is a low-scoring sport, and the team with worse chances wins often enough that nobody should be surprised. xG measures process, and process is only part of the story in a game decided by single moments.

Used properly, xG is a reading aid, not a verdict. Check it after a match to understand whether the score flattered someone. Check it over ten games to judge whether a team's form is real. Check it before a match to see which teams create and concede chances, then combine it with team news, tactics and motivation before forming any view. The fans and bettors who get the most from xG are the ones who treat it as one input among several, not as a shortcut that replaces watching the game or doing the rest of the homework.