Largest chess tournaments

The British Land UK Chess Challenge has around 70 000 British school kids playing across England in recent years.

The Supernationals III in Nashville 2005 had 5270 juniors competing.

The largest adult event would probably be the World Open in Philadelphia 1986 with 1506 players. Nick de Firmian came in first ahead of Yasser Seirawan, Jozsef Pinter, Gyula Sax, Margeir Petursson, and Ivan Farago, as well as the young Anand. In 2003, the World Open had a lot of players as well: 1462. The HB Global Chess Challange, Minneapolis, May 2005 had 1358 players (43 GMs). By comparison, there were 1135 players at Calvia Olympiad 2004, and Bled Olympiad 2002 only had 806 players.

The largest round robin tournament was probably New York 1869. There were 48 competitors who were supposed to face each other twice each. Not surprisingly not all of the games were finished. The winner was George H. Mackenzie. Another fairly large round robin was Carlsbad 1911 with 26 players.

The event with the most grandmasters would probably be one of the Olympiads. Calvia Olympiad 2004 had 250 grandmasters. Bled Olympiad 2002 only had 183 grandmasters. The European Club Cup in Rethymonon Greeece 2003 had 150 grandmasters. Aeroflot swiss, Moscow 2004 had 140 grandmasters.