How big is a avrige bee hive?

The size of a honey bee hive varies throughout the year. During the winter, the queen stops laying and the colony diminishes down to as low as around 10,000 bees, then as spring comes the queen starts laying again and the numbers increase. During the height of summer the colony would be as large as 60,000 bees -- possibly more if space permits.

If a colony gets much larger than this it becomes unstable because the queen pheromone becomes more diluted and the workers will initiate a swarm which would split the colony in two.