You may be familiar with the term xG, which has become a mainstream stat in football, used on TV and post-match coverage. But what does it actually mean, and how important is it to football clubs?

Expected goals (xG), invented in 2012 by Opta's Sam Green, measure the likelihood that a shot will result in a goal. Each shot will be given a value between zero and one; the closer the score is to one, the more likely the team is to have scored that specific chance.

How is xG calculated?

It’s determined using Opta’s historical data - reviewing how similar chances have converted. Other measuring factors typically include distance, angles, type of assist and type of shot.

What can xG tell us?

The benefit of xG in football is that it can help assess the quality of chances created, not just the final score. For example, a team with high xG but no goals likely created good chances but finished poorly. In reverse, a team with low xG but a goal may have scored from low-probability chances. Which, over time, can provide a clearer picture of performance than just results alone.

In real terms, coaches use xG to evaluate whether the team created good chances, which helps clearly distinguish performance from luck. For instance, a chance with an xG of 0.8 tells a coach their player had an 80% chance of scoring from that opportunity, highlighting someone who has put themselves into a high-quality scoring position. That said, clubs don’t rely on xG alone; it’s one tool amongst many others.

Limitations

Like most things in football, xG faces its criticism, and to a degree, the criticism can be justified. Whilst the tool is useful, it doesn’t fully capture player skill or goalkeeper ability. And it doesn’t account for game pressures or scoreline, to name a few. Which is why, as mentioned above, xG is not used in isolation.

So, does xG matter in football?

Yes, absolutely. It is widely used in professional football as it helps analyse performances more objectively and is particularly useful over multiple matches. Whilst it is not a standalone metric and of course needs human analysis, it’s an extremely useful tool with many benefits.