Semrush Sensor: what the volatility score measures and the sequence to run when rankings move

Semrush Sensor is a free SERP volatility tracker. It measures how much Google's search results moved in the last twenty four hours, reports it as a score out of ten by country, by device and by industry category, and shows which SERP features rose or fell alongside it. You use it to answer one question quickly: when your rankings move, did the whole category move with you, or is this about your site? A high Sensor reading on the day your positions dropped points at an algorithm change. A calm reading on the same day points at something you did, and that is a far more urgent investigation.

This page covers what the score measures, how to read it properly, the alternatives worth cross checking and the diagnostic sequence to run when your rankings move. For diagnosing a position rather than the weather around it, see how to diagnose a ranking and then move it.

What the score measures

Semrush tracks a large fixed set of keywords every day, records the top results for each and calculates how much the result sets changed from the previous day. More change means a higher score. The Sensor dashboard gives you several readings rather than one:

• Overall volatility by country, split between desktop and mobile. The two often diverge, and the split alone tells you where to look first.
• Volatility by industry category, such as health, finance, travel, retail and jobs and education. This is the most useful view, because updates frequently hit some categories much harder than others.
• SERP feature presence, showing the share of results containing featured snippets, local packs, shopping units, videos, reviews and so on, with the change from the previous day. A drop in clicks with stable positions is often explained here.
• Winners and losers, the domains that gained or lost the most visibility across the tracked set.
• A personal score, if you connect your own tracked keywords, which compares your movement with the category.

How to read the number properly

• Read your category, not the global figure. A quiet overall score with a spike in your own vertical is the signal that matters, and it is the one most people miss.
• Read the trend across several days. Google updates often roll out over one to two weeks, so a single day looks like noise until you see the shape.
• Treat it as weather, not as diagnosis. The score tells you whether conditions were turbulent. It does not tell you why your page moved, and the next step is always your own data.
• Compare device views. Mobile only volatility points at mobile layouts, feature changes or local results rather than at your content.
• Note the feature changes before you conclude anything. If shopping units expanded in your category, your traffic can fall while your position holds, and that is a different problem with a different fix.

Cross check with the other volatility trackers

Each tracker watches a different keyword set, so they disagree at the edges and agree when something big happens. Checking two or three is quick and makes the reading far more reliable.

Tracker	What it reports
Semrush Sensor	Score out of ten by country, device and category, plus SERP features and winners and losers
MozCast	Volatility expressed as a temperature, with feature tracking
Algoroo	A volatility index with a list of the keywords that moved
Advanced Web Ranking	Daily fluctuation by position range and by country
Accuranker Grump	A daily volatility rating by device and country

Then confirm against the primary sources. Google publishes confirmed ranking updates on its ranking updates page and reports indexing and serving incidents on the Search Status Dashboard. A confirmed update plus a category spike plus a movement in your own tracking is a complete picture; one of the three on its own is a hypothesis.

The sequence to run when your rankings drop

1. Check the volatility trackers for your category and device. Two minutes, and it decides which of the next two branches you take.
2. Check the Search Status Dashboard for an open indexing or serving incident.
3. If volatility is high: compare your movement with your category, list the pages and queries that fell, and look for what the surviving pages have in common. Hold off on large changes while an update is still rolling out, and record the baseline so you can measure the recovery.
4. If volatility is low: the cause is far more likely to be yours. Check for a deployment on that date, a robots or noindex change, a canonical change, a template error, a redirect chain, a server error spike, an expired certificate or a CDN rule. Search Console's Page indexing and Crawl stats reports will usually name it.
5. Separate position loss from feature loss. Pull impressions, clicks and average position per query from Search Console. Stable position with falling clicks means the result page around you changed.
6. Write down the date, the reading and what you found. A simple log of these events turns future incidents into a ten minute job.

Google's guide to its ranking systems is the reference for which named systems exist and what each one does, and it is more useful than most commentary when an update lands.

What Sensor is good for beyond incident response

• Setting reporting expectations. A note in a monthly report that your category saw a documented update explains movement far better than a defensive paragraph.
• Choosing when to ship. Launching a large site change in the middle of a rolling update makes both effects impossible to separate. If you can wait a week, wait.
• Spotting feature shifts early. The SERP feature view is an early warning that the click opportunity in your category is changing shape.
• Competitive reading. The winners and losers list sometimes shows a competitor gaining consistently, which is worth a closer look at what they changed.

What gets asked about Semrush Sensor

Is Semrush Sensor free?

The public dashboard is free to view, including the category, device and country breakdowns and the SERP features data. Connecting your own tracked keywords for a personal score uses a Semrush project, which sits inside a subscription.

What counts as high volatility?

Read it against the normal range for your own category rather than against a universal threshold, since some categories run hotter than others every week. Watch your category for a month, note its typical band, and treat anything clearly above that band as an event worth investigating.

Does a high Sensor score mean there was an algorithm update?

It means the results moved. Updates are the most common cause, and so are seasonal shifts in intent, layout and feature changes, and index refreshes. Confirm with Google's own update and status pages before you call it an update in a report.

Why do the different trackers disagree?

Because they watch different keyword sets, in different categories and countries, with different position depths. Agreement across two or three is strong evidence; disagreement usually means the change was narrow, which is itself useful information.

Should I change anything during a rolling update?

Keep doing the planned work that is clearly good practice, such as fixing errors and improving thin pages, and hold large structural changes until the update settles so you can read the result. Record the dates either way.

Can Sensor tell me why my page specifically dropped?

It gives you the context, which is the first half of the answer. The second half comes from your own Search Console data, your deployment history and the live results for the queries that moved. Use them together and most incidents resolve in an hour.

The result that moved in a place Sensor does not watch

Sensor measures turbulence in Google's results. When the score jumps, you check whether your pages moved. Assistants shift too, and their changes do not appear on that index: the sources they retrieve change, and a name slips off a list.

Keep a baseline for that. Ask your five buyer questions in three assistants each week and record the names. AI Knows Us keeps the history, so a change in answers can be dated and the pages behind it inspected.