Occupant Load Calculator — IBC Egress & Exit Width (Simplified)

    Estimate occupant load and minimum egress width using simplified IBC (USA) assumptions. Useful for early-stage planning and quick sanity checks.

    60 sqft/person applies to ground floor. Basement and upper floors use 30 sqft/person per IBC. Select "Custom" and enter 30 for non-ground-floor retail.

    Tips

    • Occupant load factors can be net or gross depending on use type and code edition — confirm which applies.
    • Exit width and number of exits are affected by more than occupant load (travel distance, arrangement, sprinkler systems, etc.).
    • Use this for early planning only — final egress design should be verified against the adopted code and AHJ requirements.
    • When in doubt, round conservatively (up).

    Planning tool only — simplified IBC assumptions. Not a substitute for a full code analysis or professional judgment. Verify with the adopted building code, local amendments, and your AHJ.

    Example Calculation

    Designing a 2,400 sqft office suite? Using 100 sqft/person gives an occupant load of 24. The calculated egress width (24 × 0.2″ sprinklered) is only 4.8″ for stairs — but the IBC minimum stair width is 36″ for fewer than 50 occupants, so 36″ governs. You'd need at least 2 exits (IBC requires 2 for most spaces). Always verify with the adopted code.

    Common Occupant Load Factors (Simplified)

    Space TypeLoad Factor (sqft/person)
    Assembly (chairs)7
    Assembly (tables)15
    Business / Office100
    Educational20
    Mercantile / Retail60
    Residential200

    Frequently Asked Questions

    How do I calculate occupant load?

    Divide floor area by the occupant load factor for the space type, then round up to the next whole person.

    Are these load factors always correct?

    No. Codes vary by edition and local amendments, and some use types require net vs gross area. Confirm the adopted code for your project.

    Does sprinklering change egress width requirements?

    Often, yes — some codes allow smaller width factors when sprinklered, but exceptions apply. Always verify in your adopted code.

    Is number of exits based only on occupant load?

    Not always. Travel distance, arrangement, and other conditions can require more exits. This tool uses simplified occupant-load thresholds only.

    Can I use this for permit drawings?

    Use it for early planning and checks. Final life-safety design should be confirmed by a licensed professional and your AHJ.

    Typical Results

    Office space(1,000 sq ft)10 occupants@ 100 sf/person
    Retail(1,000 sq ft)30 occupants@ 30 sf/person
    Assembly (tables)(1,000 sq ft)67 occupants@ 15 sf/person

    💡 When in doubt, use the most restrictive (highest) occupant load factor — it triggers more safety requirements.

    Common Mistakes

    • •Using net area when AHJ requires gross area (or vice versa)
    • •Applying residential load factors to commercial spaces
    • •Not accounting for mezzanines and additional floors in multi-story occupant load calculations

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