Every capacity figure you read assumes something. Ours assume sixty-inch rounds of ten with a dance floor in place — take the floor out and each hall gains roughly fifteen percent.
The number that actually decides your layout is not the guest count, it is the aisle width you are willing to live with. Thirty-six inches between chair backs is comfortable. Thirty is tight but workable. Below that, service slows down and anyone using a wheelchair is stuck.
Long tables seat more people per square foot than rounds, but they make conversation directional and they complicate service. Most rooms end up with a mix: rounds through the body of the room, a long head table, and a cabaret arc facing the stage.
