How to use this calculator
- Enter or choose measurements in.
- Enter or choose room length.
- Enter or choose room width.
- Enter or choose usable share of floor.
- Enter or choose space per person.
- The capacity updates as you type. Use Copy result or Share to keep it.
Method
Area = Length × Width; Usable = Area × Usable%; Capacity = min(⌊Usable ÷ Space per person⌋, Posted limit)
- Space per person
- floor area each guest needs in your layout
- Posted limit
- maximum occupancy set by the fire or building authority (1 ft² = 0.09290304 m²)
Worked example
- Area = 20 × 15 = 300 m².
- Usable = 300 × 85% = 255 m².
- Capacity = 255 ÷ 1 m² = 255 people.
A 20 × 15 m room with 85% usable floor holds 255 people at 1 m² each.
What the result means
Treat the result as a planning estimate for the layout you entered. The legal occupancy limit always wins, and accessibility, exits and sight lines can lower the practical number.
Assumptions and limits
- The room is a rectangle; enter the equivalent area for other shapes as length × 1.
- It does not check fire code, exit widths or accessibility; always confirm with the venue.
Questions
Why does layout matter so much?
Rows of chairs pack people close together; classroom desks and banquet rounds need much more room per guest, so the same room holds far fewer.
Where do I find the occupancy limit?
The venue should know it, and many jurisdictions require it to be posted in the room.