During every Google update, someone posts a screenshot showing their site at position 3, while a colleague in another city sees it at position 9 and a rank tracker says 14. All three can be telling the truth. Google does not show a single, fixed results page to everyone.
Location, language, device, personal search history and the gradual nature of rollouts all shape what any one person sees. That is why reports of an update's "impact" vary so much between tools, agencies and forums, and why your own experience may not match the headlines.
This guide explains each of those factors using Google's own documentation, shows how they distort update analysis, and gives you a checklist for measuring impact consistently in 2026.
Key Takeaways
- Google says relevance can depend on the user's location, language and device, so results differ legitimately between searchers.
- Google may personalise results using location, past search history and search settings, and it says users can see and control this.
- Testimony at the US antitrust trial described Navboost click data as having locale and mobile/desktop "slices", reported by Search Engine Land.
- Updates roll out over days or weeks, so two checks on different days can capture different stages.
- Consistent tracking settings (location, device, language, logged-out) matter more than any single tool.
Why one update can look so different to different people
Google's in-depth guide to how Search works says relevancy is determined by hundreds of factors, which "could include information such as the user's location, language, and device (desktop or phone)." It gives a simple example:
“For example, searching for "bicycle repair shops" would show different results to a user in Paris than it would to a user in Hong Kong.”
— Google Search Central, In-depth guide to how Google Search works
That variation exists every day, not only during updates. But when an update is rolling out, it combines with ranking changes and makes the picture much harder to read. A local business owner may see a big swing in their town while a national tracker reports a calm SERP.
The factors that change what each searcher sees
| Factor | What Google has said | Effect on update analysis | How to control for it |
|---|---|---|---|
| Location | Location can affect relevance and personalisation | Local and "near me" queries vary by city or even neighbourhood | Track from fixed locations; segment by country in Search Console |
| Language | Language is a relevance factor | Multilingual sites may see different impact per language | Analyse each language/market separately |
| Device | Desktop vs phone can change relevance | Mobile and desktop rankings can move differently | Split by device in Search Console and trackers |
| Search history and settings | Google may personalise using past history and settings | Your own browser is a biased sample | Use logged-out, neutral checks or tracking tools |
| Rollout timing | Updates roll out over days or weeks | Checks on different days capture different states | Compare full weeks after completion |
Location and localisation
Location is the most powerful of these factors for many businesses. Back in February 2012, Google's "Venice" change increased the weight of the searcher's location so that organic results for many queries began showing local businesses (see our Venice update post). Later, Google confirmed a local search update that rolled out between 30 November and 8 December 2021, which the industry nicknamed "Vicinity" because proximity appeared to carry more weight afterwards; see our post on the Vicinity local update.
Even for non-local queries, country matters. A core update can play out differently in the UK and the US because the competing pages are different. Our guide on measuring update impact across countries covers international sites in depth, and local ranking drops after an update covers map and local pack movement.
Device differences
Google moved to mobile-first indexing from March 2018, meaning it primarily uses the mobile version of content for indexing and ranking (see our post on the mobile-first indexing rollout). Rankings and SERP layouts still differ between phones and desktops, and click-through behaviour differs too.
Interestingly, trial reporting adds detail here. Search Engine Land's summary of Pandu Nayak's testimony in the US antitrust case reported that Navboost, a system using click data, has locale and mobile/desktop "slices". That is consistent with what many SEOs see in practice: an update can move mobile rankings for a page differently from desktop rankings. Treat this as context about how the system was described in court, not a guide to current weighting.
Personalisation: real, but often overstated
Google's How Search Works site says it uses "information such as your location, past Search history, and Search settings" to make results more helpful, and that "anytime we personalize Search results to be more helpful, we let you know." It also says users have "controls to turn personalization off altogether" and that "Google Search does not put people in 'filter bubbles.'"
For update analysis, the practical lesson is simple: your own logged-in browser is not a reliable measuring tool. You search for your brand and your site often, which is exactly the kind of history that can shape what you see.
Rollout timing and data centres
Updates are not switched on everywhere at once. Google's Search Status Dashboard shows rollouts lasting from under a day (the March 2026 spam update) to 45 days (the March 2024 core update). During that time, checks made hours apart may reflect different stages. For many years SEOs have also attributed some short-term ranking differences to results being served from different data centres; Google has not published details about this for current updates, so treat it as an observation rather than a documented mechanism. Our article on how Google rolls out core updates explains what is confirmed.
How to measure update impact consistently
- Start with Search Console, not screenshots. It aggregates real impressions from real searchers across locations and devices.
- Segment by country and device. Compare each segment before and after the update instead of looking at one blended number.
- Fix your rank tracking settings. Choose specific locations (city level for local businesses), device type and language, and keep them unchanged.
- Use neutral manual checks. If you must look yourself, use a private window, and remember location still applies.
- Wait for the rollout to complete. Then compare full weeks.
- Cross-check volatility tools. Different tools track different keyword sets and locations, so look for agreement rather than a single score. Our review of SERP volatility tracking tools explains their differences.
Tracking settings checklist
| Setting | Recommended choice | Why it matters |
|---|---|---|
| Location | City or postcode for local businesses; country for national sites | Local results change with distance |
| Device | Track mobile and desktop separately | Rankings and layouts differ |
| Language | Match your audience's interface language | Language is a relevance factor |
| Frequency | Daily during rollouts, weekly otherwise | Captures movement without overreacting |
| Keyword set | Stable list including branded and non-branded terms | Changing the list changes the averages |
If you need a refresher on tool setup, our rank tracking guide walks through it, and the local SEO guide covers local visibility tracking.
Common mistakes
- Judging an update from your own phone. Personal history and location skew the result.
- Comparing tools with different settings. A desktop US tracker and a mobile UK tracker will disagree by design.
- Blending all countries together. A loss in one market can hide behind a gain in another.
- Ignoring device splits. Mobile-only drops often point to layout or SERP feature changes.
- Calling the impact on day two. Rollouts are gradual; wait for completion.
Related Guides
- Not Every Traffic Change Is an Update: SERP Layout Changes Explained
- Search Intent Shifts During Core Updates
- How Often Does Google Release Updates? Data From 2021-2026
Frequently Asked Questions
Why do I see different rankings from my rank tracker?
Your results can reflect your location, device, language and search history, while the tracker uses fixed settings. Both can be accurate for their context.
Does Google personalise search results?
Google says it may use location, past Search history and settings to personalise, tells you when it does, and lets you turn personalisation off.
Can an update affect mobile and desktop differently?
Yes. Rankings and layouts differ by device, so always split Search Console data by device when analysing an update.
Do updates hit every country at the same time?
Rollouts happen over days or weeks and competing pages differ by country, so impact can vary by market. Analyse each country separately.
What is the most reliable way to measure update impact?
Search Console data segmented by country and device, compared over equal periods after the rollout completes, backed by consistently configured rank tracking.
Conclusion
Update impact looks different from place to place because Google's results genuinely differ by location, device, language and personal context, and because rollouts take time. Measure with consistent settings and segmented Search Console data, and you will see the real effect rather than a single, misleading snapshot. For help with local visibility, explore our local SEO services or request a quote.
