The numbers that should worry every ecommerce team
A new audit of eight U.K. ecommerce brands has found GA4 telling a very different story from store order records. At one retailer, GA4 reported revenue down 68% a day between Christmas Day 2025 and January 4, 2026. The store’s own records showed a fall of 13%.
GA4 captured 81% of that retailer’s web orders in Q4 2024, 41% in Q4 2025, and just 32% over the Christmas window. At a second brand, GA4 showed revenue down 69% while net sales actually rose 18.5%.
Where the gaps came from
The audit points to setup problems rather than a Google algorithm failure. Cookie banners that switched off after hitting a page-view allowance, a five-week purchase blackout followed by late backfill, duplicate transaction IDs, and a flood of bot sessions all distorted reporting.
At one store, GA4 recorded zero purchases from October 28 to December 4, 2025, while the store logged 2,215 orders. GA4 later loaded 1,261 orders in a single day, including 1,000 with order numbers from inside the gap. Another retailer had 657 order numbers counted more than once in Q4 2025, adding 735 phantom purchases to its total.
Why this breaks budget decisions
When GA4 undercounts, it makes winning channels look weak. In the audit, GA4 showed Google Ads return on ad spend falling from 8.07 to 4.79. Matched to store orders in a multi-touch attribution tool, it rose from 4.42 to 7.93 on 20% less spend.
Cutting either paid or organic budgets on GA4’s numbers alone would have pulled money from channels that were working. That is why the audit recommends judging channels together against store orders.
Run this check before peak
- Export weekly web orders for Q4 2024 and Q4 2025, excluding marketplace, subscription and manual orders.
- Pull GA4 purchases for the same weeks as distinct transaction IDs on purchase events, not the transactions metric.
- Divide GA4 purchases by store orders. Step changes, near-zero weeks, or a week above 100% are tracking problems.
Also watch for sessions dropping out in blocks that start or end on the same date each month, and for spikes in Direct traffic that store orders don’t follow.
Use Search Console as an early warning
Search Console counts clicks regardless of what your site tags are doing. Divide GA4 Google organic sessions by Search Console clicks each week. In one blackout week, Google sent 4,244 clicks while GA4 recorded only 57 organic sessions.
Make the store the source of truth
Before peak, agree that orders and revenue come from the store, GA4 explains behaviour and trends, and ad platforms report what they claim. Lead with the capture rate. “GA4 recorded 41% of our web orders this quarter, down from 81% last year” is a sentence any finance director understands.
For a more resilient setup, send purchase events server-side from the store’s own system, keyed on the order number. Keep the browser tag for behaviour, and remember server-side tracking does not remove your consent obligations.
Source: Search Engine Journal
