Exit Door Quantity Calculator

1. Adjusted occupant load
   OL_adj = OL × (1 + Safety% ÷ 100)
2. Required total egress width
   W_req = OL_adj × EgressFactor
3. Effective width per door
   W_door,eff = DoorClearWidth × UsableWidthFactor
4. Doors needed by width capacity
   N_width = ceil(W_req ÷ W_door,eff)
5. Minimum exits by occupant-load thresholds
   N_min = 1 (≤49), 2 (50–500), 3 (501–1000), 4 (>1000)

---

Final recommendation: N = max(N_width, N_min). This is a planning estimate and does not replace code analysis for travel distance, door swing, separation, or accessibility.

• Select Direct occupant load or compute it from areas and load factors.
• Choose the egress component. Use the typical factor for level egress or stairs, or enter your own.
• Enter door clear width and a usable width factor to represent effective flow width.
• Add a safety margin if you expect load variability or future changes.
• Click Calculate Exit Doors. Results appear above the form under the header.
• Use Download CSV or Download PDF to save the calculation record.

Estimating the number of exit doors is more than a simple headcount. A strong egress plan considers how many people may need to move, how quickly they can pass through openings, and whether the layout can support orderly flow without congestion. This calculator provides a planning-level recommendation by pairing two common checks: a minimum-exit threshold based on occupant load and a width-capacity check based on effective door width.

Start by establishing an occupant load you can defend. If you already have a confirmed occupant load from design criteria, use the direct method. If you are still in early planning, compute occupant load from areas and load factors so your assumptions are transparent. The area method sums each space as area ÷ load factor, then rounds up. This makes it easier to track how office zones, lobbies, storage rooms, and assembly spaces contribute to total demand.

Next, confirm the egress component and width factor. Level egress paths typically use a smaller width-per-person factor than stairs, because stairs reduce speed and increase spacing. The calculator allows you to override the factor to match local guidance or project-specific policies. A safety margin can then be applied to reflect uncertainty, future tenant changes, or peak-event conditions.

Door width in drawings is not always the width that actually carries people. Frames, hardware, clearances, and behavior reduce usable flow. For that reason, the usable width factor converts clear width to an effective width per door. The required total width is calculated from adjusted occupant load multiplied by the selected width factor, then divided by effective door width to estimate the number of doors needed for capacity. The final recommendation is the larger of the capacity result and the minimum-exit rule.

Example workflow: assume an occupant load of 180 people, a level-path factor of 0.15 in/person, door clear width of 1000 mm, usable factor of 0.90, and a 15% safety margin. The calculator computes the required total egress width, derives effective width per door, and recommends two doors, aligning with the minimum-exit threshold for that load. Use the example table above to compare multiple scenarios and validate your assumptions quickly.

Treat this output as a structured estimate for coordination, then confirm full compliance using your local requirements for travel distance, exit separation, swing direction, hardware, accessibility, and special hazards.

1) What does “recommended exit doors” represent?

It is the higher value of two checks: doors needed to satisfy egress width capacity, and the minimum number of exits based on occupant-load thresholds.

2) Can I use this calculator for any building type?

You can use it for early planning across many occupancies, but you must verify final requirements because local rules vary by occupancy, hazard level, and layout constraints.

3) Why is there a usable width factor?

People do not use the full clear width perfectly. Frames, hardware, and crowd behavior reduce effective flow, so the usable factor gives a more realistic capacity estimate.

4) When should I choose the stairs option?

Select stairs when the controlling egress path is stairways or when you are sizing stair egress width. Stairs typically require more width per person than level routes.

5) How should I set the safety margin?

Use 0–10% when loads are well defined, and 10–20% during early planning or where tenant use may change. Avoid excessive margins that distort downstream design decisions.

6) Does this replace a full egress analysis?

No. It estimates door count using occupant load and width capacity. You still must check travel distance, exit separation, door swing, fire ratings, accessibility, and authority guidance.

7) Why might I still need more doors than calculated?

Layout, compartmentation, tenant demising, and travel-distance limits can force additional exits. Operational needs like crowd management or phased evacuation may also increase door counts.