Occupant load & egress

Occupant load from IBC 2024 Table 1004.5, then the required egress width, the minimum number of exits and the travel distance limit — with the gross/net basis stated on every answer and the clause cited on every line.

Start

Give both and the governing code is resolved for you — the edition your state enforces, and for a house the residential code it is permitted under as well as the building code the engineered design runs on. Leave them and you still get the occupant load; only the citation depends on where you are.

The 38 functions IBC Table 1004.5 gives an area factor for, with the ones usual for this occupancy first. ⚠ The grouping is ours, not the code's — every function stays selectable, because §1004.5 assigns the factor by what the SPACE is, not by how the building is classified. Three further rows exist and are not here — see “What this will not tell you”.

⚠ This space, not the building. The occupant load is worked out per room from that room's own function, so the area is the room's — a storey is several of these added together (§1004.2), which is not what this page does. Most Table 1004.5 factors are on gross area and several are on net; the answer says which one applies.

The building — for egress width, exits and travel distance

The reduced capacity factor needs both, and is not available to Group H or Group I-2 at all. Ticking only the sprinkler leaves the base factor in place — deliberately.

What it does

Enter a floor area and pick a function of space, and this returns the occupant load from IBC 2024 Table 1004.5 — then, if you name the occupancy group, the required means-of-egress width from §1005.3, the minimum number of exits from Table 1006.3.3, and the exit access travel distance limit from Table 1017.2. Every number carries its clause.

The occupant load factor is on gross area, or on net — never both

Table 1004.5 publishes 38 factors and each one is qualified gross or net. Business areas is 150 gross; a classroom is 20 net. Feeding a gross area to a net factor overstates the occupant load, and no downstream check can detect it, because both numbers are areas in square feet. This calculator states the basis on every answer for that reason.

The sprinkler on its own does not reduce the egress width

§1005.3.1 sizes stairways at 0.3 inch per occupant and §1005.3.2 sizes everything else at 0.2. The familiar reduced figures — 0.2 and 0.15 — come from Exception 1, which requires an automatic sprinkler system and an emergency voice/alarm communication system, and is not available to Group H or Group I-2 at all. Applying it on the sprinkler alone under-sizes every stair and door in the building by a third.

What this will not tell you

Three rows of Table 1004.5 are not in the picker, because the table itself sends them somewhere else and an area factor is not the method:

  • Assembly with fixed seats — Section 1004.6
  • Concentrated business use areas — Section 1004.8
  • Mall buildings—covered and open — Section 402.8.2

A function not listed in Table 1004.5 is the building official's call, not ours. §1004.5 says so: where an intended function is not listed, the building official establishes one based on the listed function it most nearly resembles. That is why there is no free-text box here.

One space, not a storey. Cumulative occupant loads (§1004.2), multiple-function spaces (§1004.3) and multiple occupancies (§1004.4) are how a real storey is assembled, and they are not here. Nor is the distribution of the required width across the actual exits (§1005.5), or egress convergence (§1005.6).

Nothing is reduced or increased. The single-exit allowances of §1006.3.4 can permit fewer exits than Table 1006.3.3 requires; the increases of §1017.2.1–.3 can permit longer travel. Neither is applied — the tabulated requirement is what you get, which is the conservative side.

The editions we hold, and no others. Chapter 10 is read into our code knowledge base per edition — IBC 2018, 2021 and 2024 today. A jurisdiction on an edition we do not hold is refused by name, with the edition its code adopts stated, rather than answered from a different one. That matters more than it sounds: the 2015 and earlier editions number this table 1004.1.2 rather than 1004.5, and put business areas at 100 ft² per occupant against 150 from 2018 on — a 50% difference in the occupant load of every office, which is not something to paper over.

State amendments are applied as amendments. Where a state changes a value we carry the change against the model code rather than assuming none exists — Florida, for one, sets information technology equipment facilities at 500 ft² per occupant where the IBC says 300.

Tired of picking the state?

On a project, the code basis comes from the address instead of a dropdown: confirm it once and the governing edition — and, for a dwelling, the residential code it is permitted under alongside the building code the engineered design runs on — is stored with the project and reused by every calculation on it, so two calcs on one job cannot end up on different editions. PerCode AEC is where the whole storey gets taken: every space at once, cumulative and multiple-function occupant loads, the required width distributed across the exits you actually drew, and the sealed report.

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