Estimates of numbers who marched on Tuesday vary widely

How many protesters took part in this year's July 1 march? The answer depends on whom you ask.

The annual pro-democracy march's organiser, the Civil Human Rights Front, put the turnout at 510,000, while the police said the number of marchers peaked at 98,600. They didn't offer an overall total.

Two academics from the University of Hong Kong estimated the total was between 122,000 and 172,000, while a method employed by the put the figure at 140,408. The wildest estimate, posted online, was 1.3 million.

The organisers said their figure was based on the average from three teams of volunteers counting at different points along the route, a method dismissed by University of Hong Kong statistician Professor Paul Yip Siu-fai as "almost impossible". Their base average was about 340,000, which the front multiplied by 1.5 on the grounds many protested on footpaths or outside the main route. That produced its final figure of about 510,000.

The 1.3 million estimate was based on a condensed version of a 90-minute YouTube video shot from a position above Victoria Park, where the march started.

Comments accompanying the film said the estimate was reached by assuming there were 20,000 people on each of the soccer pitches inside the park, or about six people per square metre - as crowded as an MTR compartment during peak hours.