How big is Luneta? Forgive me for citing Wikipedia, but here are the stats:
The total area, from Taft Avenue to the Quirino Grandstand, is 54 hectares.
The Northeastern section, which extends from Taft Avenue to Maria Orosa St., is 16 hectares.
The Central section, from Maria Orosa St. to Roxas Boulevard, is 22 hectares: this part is where the dancing fountain, the Japanese garden, the Rizal Monument and the giant flagpole can be found.
The Southwestern section is the 10-hectare open field that ends at the Quirino Grandstand and the Manila Ocean Park.
One hectare is equivalent to 107639.104 square feet; assuming that one person occupies two square feet, that would translate to 53, 819.552 persons per hectare.
So: if the Southwestern section is fully occupied, that would be about 533, 819 people. But we’re talking about people standing up, side to side, as in an elevator lift (the calculations were for people inside an elevator lift).