What is the SEMrush Sensor?

The SEMrush sensor is a tool created by SEMrush to measure volatility in Google's search algorithm. The main driver of volatility in Google's search algorithm are the regular algorithm updates made by Google. Therefore, the SEMrush Sensor is an ideal tool for detecting changes to Google's search algorithm.

Here's a live view of the SEMrush sensor with today's volatility score:

How can I use the Sensor to detect changes in Google's search algorithm?

Each day, SEMrush publishes a volatility score. The higher the score, the more volatility in Google's search results. In general, scores of 5 and above are considered high volatility, and suggest a Google search algorithm update. Here's a screenshot of SERP volatility for a 30 day period in August. We've highlighted the orange data point on the chart with a Sensor score of 6.2. Any score at this level is likely tied to an algorithm update.

When it detects a change, SEMrush shares any publicly known information about the algorithm change. To find the details about a specific algorithm change, you can look at the bottom of the report for a section that looks like this:

It's important to keep in mind that Google makes changes to specific pieces of its algorithm, as well as general algorithm updates that impact all search results. SEMrush allows you to filter and compare specific subject categories, devices, and countries to identify more granular updates to Google's search algorithm. We recommend that you monitor the score specific to your website's industry and geography.

SEMrush's Sensor also publishes day-to-day changes in specific search engine result page (SERP) features:

How is the Sensor score calculated?

To calculate the Sensor score, SEMrush records organic search results for a fixed basket of keywords at the beginning and end of each day. Here's a quote from SEMrush's website:

"For each keyword, we do a per-item comparison of "today’s" results vs "yesterday’s" results. We measure how much has changed in a day using Levenshtein distance (as a basis) and normalization. The total value of the score reflects the total search volatility for the day."

How can I use the Sensor to detect changes for my website?

If you have an SEMrush account, the SEMrush Sensor report will have a Personal Score tab that is linked to your website. If not, you can visit the page and enter your domain to see the Sensor score for your domain (note: you will still have to log-in and sign up for a free SEMrush trial to see a score).

This report will calculate a daily volatility score specifically for your website based upon the keywords that you've uploaded to SEMrush. The more keywords you have in the system, the more accurate your score will be.

How else can I stay informed about Google search algorithm updates?

Other than the SEMrush Sensor, we recommend following the right accounts on Twitter. Industry experts and Google itself will often announce search algorithm changes. Here are the accounts we suggest starting with: