Why analytics numbers differ between tools

Tools recognise visitors differently, and consent banners, ad blockers, bots and time zones all affect the totals. A gap of 5–15% is common (more if one tool only loads after consent) and does not automatically mean tracking is broken.

Identity and cookies

GA4 recognises visitors with cookies; PureMetrix counts them cookieless with a salt that changes daily. So the two tools count slightly different groups of people, and they handle visitors on several devices differently. Unique visitor totals will not match exactly.

Consent and tags

If Google Analytics only loads after visitors click “Accept”, everyone who declines disappears from GA but can still be counted by cookieless PureMetrix. That makes PureMetrix look "high" compared with GA.

Ad blockers

Ad blockers affect tools unevenly, especially those that send data to third-party domains. The same-origin /px proxy narrows the gap for PureMetrix.

Bots and staff

Role exclusions keep logged-in staff out of PureMetrix; other tools may still count them. Automated requests (e.g. scheduled tasks and uptime monitors) are also filtered differently from tool to tool.

How to compare fairly

Pick one landing page URL.
Use the same time zone and date range.
Compare trends and goal rates, not total visitor counts.
Write down the consent and proxy settings in your summary.

When to really investigate

Investigate sudden drops after an update to your website, missing WooCommerce purchase events, or zero traffic from a campaign you know is running. Don’t call an emergency meeting over a stable 8% difference between tools.

Differences between methods are normal

Cookies vs daily salted hashes, bot filters, time zone boundaries and consent mode all shift the counts. A stable gap in the single digits or low double digits between GA4 and PureMetrix is common. A sudden 40% drop usually means a missing snippet, a blocked proxy or a new consent default—nothing mysterious.

Reproduce the issue in a private window, watch the Network tab in your browser’s developer tools, and compare the same minute in both dashboards. Fix the tracking setup before you debate methods.

What to tell stakeholders

Agree that goals and revenue trends are what counts. Identical visitor numbers across different tools are a poor success measure. Point to the GA4 accuracy notes when managers expect two tools to match exactly.

Checklist when the gap suddenly grows

Is the snippet in the page template?
Does the proxy return status 200?
Is a consent setting newly blocking tags?
Has the time zone or currency changed?
Was a goal renamed?
Is the staff exclusion switched off in one of the tools?

Unique visitors counted with PureMetrix’s daily salt will not match GA cookie users. Explain this once, then check the tracking setup. Linking the GA4 accuracy notes in your internal documentation saves repeating the explanation.

How to present it to management

Agree on conversion trends and spot checks of revenue against your shop as the measure of success. Don’t accept identical visitor numbers across providers as a success criterion—it is a trap.

Currency and time zone traps

Shops that compare WooCommerce (shop time zone) with analytics (account time zone) see drops overnight that aren’t real. Align the time zones before discussing methods. Revenue including tax in one tool and excluding tax in another causes similar false alarms—note which is which.

Sampling and thresholds

Some large GA setups only analyse a sample of the data; cookieless tools may not offer the same detailed exploration reports. Comparing a sampled GA exploration with PureMetrix goals is comparing apples and oranges. Use unsampled exports or simple GA standard reports when you compare.

Also check that both tools exclude (or include) logged-in staff the same way before you call it a method difference.

Consent mode differs by region

GA4 Consent Mode may estimate missing data differently depending on the region, while PureMetrix simply counts every visit that reaches it, with no consent-based estimates. Comparisons across regions therefore differ more than comparisons within one region. Split the data by region before concluding that tracking is “broken.”

If management needs a single slide, show PureMetrix goal completions next to the conversions reported by your ad platform—not raw visitor totals from two different methods.

Write the expected range of the gap into the contract or statement of work (e.g. 5–15%), so the client doesn’t treat every difference as a breach.

Changes to bot protection

Switching on strict bot protection can lower both server logs and analytics at the same time. Announce such changes so dips in PureMetrix aren’t mistaken for a tracking failure.

Set date ranges and time zones explicitly when managers compare exports; a mismatch between UTC and Europe/Berlin creates fake Monday crises.