npxG — Non-Penalty Expected Goals

Definition

Non-Penalty Expected Goals (npxG) is simply xG with penalty kicks excluded from the total. Since penalties have a relatively fixed xG (~0.76–0.79 depending on the model), they can significantly inflate a player's or team's xG total without reflecting open-play chance creation or finishing.

History & Origins

npxG emerged almost simultaneously with xG itself as analysts recognized the distortion penalties cause. When comparing the chance creation of two teams or the output of two forwards, a player who takes 10 penalties per season has an automatic ~7.6 xG advantage that says nothing about their open-play quality.

The convention became standard across analytics platforms by the late 2010s. FBref, Understat, and StatsBomb all report npxG alongside xG as a default.

How It Works

Simply subtract all penalty kick xG values from the total:

npxG = total xG - sum of xG from penalties

The same logic applies to goals: npG (non-penalty goals) strips out converted penalties.

A common derived metric is npxG per 90 minutes, which normalizes for playing time and is widely used for player comparison.

Why It Matters

• Player comparison: Comparing two strikers' goal output is misleading if one takes all the team's penalties. npxG and npG level the field.
• Team analysis: A team's open-play chance creation is better reflected by npxG than total xG
• Transfer valuation: Clubs and analysts use npxG/90 as a key metric for evaluating forwards, since penalty duties are often reassigned after a transfer

Limitations & Debates

• Penalty generation is a skill: some players earn penalties by running at defenders in the box. Stripping penalties entirely ignores this contribution. Some analysts argue for a "penalty won" credit separate from the penalty xG itself.
• Penalties are goals too: in actual standings, goals from penalties count just as much. npxG is an analytical lens, not a better version of xG — both are useful for different questions.
• Inconsistent treatment of penalty rebounds: some models count follow-ups to saved penalties differently

Relationship to Other Metrics

• xG (see xG - Expected Goals) → the base metric, npxG is a filtered version
• PSxG (see PSxG - Post-Shot Expected Goals) → can also be computed as npPSxG for non-penalty shots
• xG overperformance → most meaningful when computed as npG - npxG, removing penalty variance

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Tags: #football #analytics #xG #npxG #metrics