Why this metric matters so much?
Sessions before purchase help explain buying friction. Marketing loves it. Product loves it. I’ve seen it drive changes in onboarding and remarketing.
What usually breaks the calculation?
Most mistakes come from counting too much.
- Sessions after purchase
- Multiple purchases per user
- Sessions from different time windows
The metric quietly inflates and stops reflecting reality.
What GA4 export forces you to respect?
Time order matters.
You must clearly define the first purchase and ignore everything that comes after.
How I calculate it now
For each user, I find the first purchase timestamp and count only sessions before it.
It’s stricter — and far more useful for business decisions.
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