How is occupancy load calculated?

Occupancy load = Floor area (sq ft) ÷ Load factor (sq ft per person). The load factor is set by the International Building Code (IBC) Table 1004.5 based on the occupancy type. For example, a restaurant dining area uses 15 sq ft per person. A 1,500 sq ft dining room has a maximum occupancy of 1,500 ÷ 15 = 100 people.

What is the IBC occupancy load factor for restaurants?

Per IBC Table 1004.5, restaurant dining areas use a load factor of 15 sq ft per person (gross). A standing/cocktail area uses 5 sq ft per person. Kitchen/food prep areas use 200 sq ft per person. These factors determine the maximum legal occupancy for fire code and egress design purposes.

What is the difference between gross and net floor area for occupancy?

Gross floor area includes all space within the exterior walls including walls, columns, restrooms, and circulation. Net floor area excludes non-occupiable spaces like walls, columns, fixed equipment, and areas not accessible to occupants. Some IBC occupancy types use gross area; others use net. The IBC table specifies which applies for each occupancy type.

What is the occupancy load for an office?

Per IBC Table 1004.5, business/office occupancy uses 100 sq ft per person (gross). A 2,000 sq ft open office has a maximum occupancy of 20 people. Conference rooms use 15 sq ft per person net. These are code minimums — actual planned occupancy may be lower based on furniture and workstation layout.

Who determines maximum occupancy for a building?

Maximum occupancy is determined by the Authority Having Jurisdiction (AHJ) — typically the local fire marshal or building official. They apply IBC or local code load factors to approve a Certificate of Occupancy. The posted occupancy load on your fire permit is the legal maximum — exceeding it violates fire and life safety codes and can result in fines or closure.

Does furniture reduce occupancy load?

For some occupancy types, fixed furnishings reduce the net usable floor area, which reduces the calculated occupancy. However, the IBC load factor already accounts for typical furniture density in most cases. For spaces with unusual fixed seating (theaters, stadiums), the actual seat count is used instead of the area-based formula.

Occupancy Load Calculator — IBC Maximum Occupancy per Room

Occupancy Type

Area type: Gross

Floor Area (sq ft)

ft²

Gross or net area depending on occupancy type

Number of Rooms / Spaces

Calculate aggregate for multiple identical spaces

Safety Buffer

Many venues operate below code maximum for safety

IBC Load Factor

15 sq ft / person

Assembly — dining (gross)

Maximum Occupancy Load

—

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IBC Table 1004.5 — Occupancy Load Factors

The International Building Code (IBC) Table 1004.5 sets the minimum floor area per occupant for egress design. These factors are used by architects, fire marshals, and building officials to determine the legal maximum occupancy.

Occupancy Type	Load Factor	Area Basis
Assembly — concentrated (theater, worship)	7 sq ft/person	Gross
Assembly — dining / restaurant	15 sq ft/person	Gross
Assembly — standing / cocktail area	5 sq ft/person	Gross
Assembly — unconcentrated (tables)	15 sq ft/person	Gross
Business / Office	100 sq ft/person	Gross
Conference room	15 sq ft/person	Net
Educational — classroom	20 sq ft/person	Net
Mercantile — retail (ground floor)	30 sq ft/person	Gross
Mercantile — retail (upper floors)	60 sq ft/person	Gross
Industrial — general manufacturing	100 sq ft/person	Gross
Warehouse / storage	500 sq ft/person	Gross
Kitchen — commercial food prep	200 sq ft/person	Gross

Sources & Methodology

✓Load factors sourced directly from IBC Table 1004.5 (2021 edition) and NFPA 101 Life Safety Code. Updated March 2026.

📋

IBC 2021 — Chapter 10, Means of Egress (Table 1004.5)

International Building Code occupant load factor table — official source for all load factors used in this calculator

📊

NFPA 101 — Life Safety Code

National Fire Protection Association life safety code — parallel occupancy load requirements used alongside IBC

Methodology: Occupancy Load = Floor Area (sq ft) ÷ IBC Load Factor (sq ft per person), rounded down to nearest whole person. For multiple rooms: total load = per-room load × number of rooms. Safety buffer applied as a multiplier to the code-calculated maximum. Always verify with your local Authority Having Jurisdiction (AHJ).

⏱ Last reviewed: March 2026

How Occupancy Load Calculations Work

Occupancy load — also called occupant load — is the maximum number of people permitted in a space at one time. It's a fundamental fire and life safety calculation used to determine the number and width of exits required, sprinkler system design, and posted fire marshal limits.

The Basic Formula

Occupancy Load = Floor Area (sq ft) ÷ Load Factor (sq ft per person)

Example: Restaurant dining room, 1,500 sq ft, IBC load factor = 15 sq ft/person
Occupancy Load = 1,500 ÷ 15 = 100 people maximum

Example: Open office, 3,000 sq ft gross, IBC load factor = 100 sq ft/person
Occupancy Load = 3,000 ÷ 100 = 30 people maximum

Gross vs. Net Floor Area

Gross area includes the total floor area within the exterior walls — walls, columns, mechanical spaces, restrooms, and circulation paths included. Net area is only the actual usable space accessible to occupants, excluding walls, columns, and fixed equipment. The IBC table specifies which basis to use for each occupancy type — using the wrong basis produces an incorrect occupancy calculation.

When Multiple Occupancy Types Exist

Many buildings have mixed uses — a restaurant with a bar area and a kitchen, for example. Each area must be calculated separately using its specific load factor, then the loads are summed for the total building occupancy. The egress system must accommodate the aggregate occupant load.

⚠️ Always Verify with Your AHJ: This calculator uses the 2021 IBC as a reference. Your jurisdiction may have adopted a different code edition or local amendments. The Authority Having Jurisdiction (local fire marshal or building official) has final authority on occupancy load determinations. Always get an official sign-off before posting an occupancy limit.

Frequently Asked Questions

Occupancy load = Floor area ÷ IBC load factor. The load factor (sq ft per person) comes from IBC Table 1004.5 and varies by occupancy type. A 1,500 sq ft restaurant dining area (15 sq ft/person) has a maximum occupancy of 100. Always use the correct gross or net area basis specified for your occupancy type.

Restaurant dining areas use 15 sq ft per person (gross) per IBC Table 1004.5. Standing or cocktail areas use 5 sq ft per person — much denser. Kitchen/food prep areas use 200 sq ft per person since they have limited occupancy. A restaurant with a 1,200 sq ft dining room, 300 sq ft bar, and 400 sq ft kitchen would have a combined occupancy of 80 + 60 + 2 = 142 people.

Business/office occupancy uses 100 sq ft per person (gross) under IBC Table 1004.5. A 5,000 sq ft open office has a maximum code occupancy of 50 people. Conference rooms are calculated at 15 sq ft per person net. Note that planned occupancy (workstations) may be much lower than code maximum — the code figure is used for egress design, not desk planning.

Yes — exceeding the posted occupancy limit is a fire and life safety violation. It can result in fines, immediate closure by the fire marshal, and personal liability if an incident occurs. The posted occupancy limit on your fire permit is the legal maximum. Many venues operate with a 10–20% buffer below the code maximum as a practical safety measure.

IBC requires: 1 exit for occupancies under 50 people, 2 exits for 50–499 people, 3 exits for 500–999 people, and 4 exits for 1,000+ people. Exit width is also calculated from occupancy load — each exit must provide sufficient clear width per the IBC egress capacity factors. This is why accurate occupancy calculation is critical to building design.

The Authority Having Jurisdiction (AHJ) — typically the local fire marshal or building official — makes the final determination. They review plans, apply the applicable code edition, and issue a Certificate of Occupancy with the posted maximum. This calculator uses IBC 2021 as a reference — your jurisdiction may use a different code edition or have local amendments.

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