Calculators: room capacity and tables

Two calculators: the building code's planning figure for a room with no posted occupant load, set beside your guest count; and the tables and chairs your count needs, with the floor they take.

1. Room capacity

Answers: how many people the code's planning factors put in a room of your size and layout, and how that compares with a posted sign and with your guests. Used in Venue and layout. Measure in feet. Enter the length and width, or the area if the venue gives it.

Assumptions behind the numbers

• The factors are the International Fire Code's Table 1004.5 for assembly without fixed seats: 15 square feet net per person for tables and chairs, 7 for chairs only, 5 for standing space. Washington State's adoption of the 2021 code prints the table (WAC 51-54A-1004), and the 2024 model code keeps the same three figures (checked 2026-10-27).
• Net floor area is the room minus the space no one can stand or sit in. The Illinois State Fire Marshal's guide lists a bar, pool tables, storage rooms, washrooms and columns as examples (Illinois SFM's occupant load guide). Tables and chairs are not subtracted; the 15-square-foot factor already allows for them.
• The figure is rounded down to a whole person.
• A posted occupant load governs where one exists. Fairfax County's Fire Marshal describes the sign, posted near the main exit of an assembly room of 50 or more (Fairfax County's assembly occupancy page). The sign also reflects exits and the approved layout, which this calculator does not see.

2. Tables and chairs

Answers: how many tables and chairs your guests need at one table size, and the floor those tables take. Used in Venue and layout.

Assumptions behind the numbers

• Seats per table are GoFoodservice's standard figures: 48-inch round 6, 60-inch round 8, 72-inch round 10, 6-foot table 6 to 8 and 8-foot table 8 to 10, the higher number with a chair at each end (GoFoodservice's table size guide). Party Rental Ltd. gives ranges two higher for rounds and says wide chairs and table decor reduce the count (Party Rental Ltd.'s seating guide). We use the lower, comfortable figure.
• The floor area per table with its chairs is one rental company's figure: 81 square feet for a 48-inch round, 100 for a 60-inch round, 121 for a 72-inch round, 83 for a 6-foot table and 98 for an 8-foot table (Curated Events' space guidelines). It is a layout check, separate from the code's capacity figure: it leaves out aisles, the buffet, a dance floor and the path to the exits.