My rally crowd is bigger than your rally crowd. How to easily guesstimate crowd size

Determining crowd size has always been a challenge when reporting an event such as a protest or campaign rally. Opposing sides either inflate or downplay the number to serve their interest.

The common practice and easiest way is to ask organizers and the police officer in charge of crowd control or monitoring. But how do we verify or validate their estimates? In cases of anti-government protests, organizers often accuse the police of downplaying crowd size.

The standard way of estimating crowd size was formulated in the 1960s by, who else, a journalist who taught at the University of California, Berkeley, during protests against the Vietnam war. Herbert Jacobs saw students protesting at a plaza that had a grid. He counted the students that were in a few squares and then averaged it before multiplying that number with the total number of squares. He also came up with a crowd density formula on the number of people by square feet. This process is called Jacobs’ Method.

ESTIMATING CROWD SIZE. The MapChecking website simplifies the estimating of crowd size at a given location.
ESTIMATING CROWD SIZE. The MapChecking website simplifies the estimating of crowd size at a given location.

There’s a tool that simplifies that process – the MapChecking website. It was built by a French developer after hearing supporters of François Fillon claim that he could gather 200,000 at Place du Trocadéro. Bullshit, he thought, and built MapChecking.

It’s easy to use, you just define the area of the gathering by clicking on the map and then indicate the density of people (helpful adjustment in today’s time of social distancing) and you get a crowd estimate.

This tool would come in handy when we start gathering in person again for political campaigns and handlers start inflating crowd size estimates on their social media posts and press releases.

I used the tool to verify the 80,000 crowd estimate at the Plaza Independencia in Cebu City when President Duterte endorsed local candidates during the PDP-Laban sortie on February 24, 2019.

Organizers and police projected the crowd to be at 80,000. The MapChecking site indicates that the estimate is plausible. If people crowded the entire area – not mosh pit level or literal packed-like-sardines crowding – at about 2 or 3 people per square meter, you’d arrive at estimates close to what was reported. A reporter present during the event would be able to use the site for a more accurate guesstimate.

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