How many people a space holds
Pick the use and type the floor area. Get the occupant load, the exits that number needs and a first exit width.
Occupant load and the way out
Every code sizes exits from the number of people a space is designed for, and that number comes from the floor area divided by an occupant load factor for the use. A standing assembly packs far tighter than an office.
The factors and the exit rules differ between codes, and the calculator uses common values for a first check: when two exits are needed, how wide they add up to, and how that changes as the load grows.
Travel distance, dead ends, door swing and corridor width are the rest of the picture. Use the load here to lay out the plan, then check it against the code that applies.
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The numbers are done. Now the image.
Turn the sketch, plan or model into a render the client can react to.