Why does this metric feel obvious?

“Items per order” sounds like school-level math. I’ve seen it calculated in five minutes — and questioned for months after.

Where the trap hides?

GA4 stores items at the item level.

  • One order = many rows
  • One product = many events
  • One mistake = inflated averages

If you skip order reconstruction, the number lies.

What needs to happen first? You must rebuild the order.

  • Group by transaction_id
  • Count items inside the order
  • Remove duplicates

Only then do you touch averages.

How I keep it clean?

I never aggregate items globally. Orders first, metrics later. This single rule saved me from countless “why is this number so high?” meetings.

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