How many people attended the biggest free concert ever?

How to get close to this number

The venue sets the ceiling. A free concert on a large urban beach is limited by how many people physically fit on the sand and the surrounding streets, which for a beach of that size runs into the millions. Ticketed stadium shows top out at a hundred thousand; only a free public space can produce a figure two orders of magnitude higher.

Free admission is the structural condition rather than a detail. Without tickets there is no gate, no capacity enforcement and no count — which is precisely why these records dwarf ticketed ones and also why they are estimates rather than measurements. The largest crowds in history are always the ones nobody was counting.

The comparison in the explanation gives it scale: roughly the population of a major European capital, on one beach, at one time. Crowd estimates of this size are derived from aerial photography and density assumptions, and they vary substantially between methods — so treat the figure as a well-attested order of magnitude rather than a headcount.