Emergency Shelter Capacity Calculator
Calculate the maximum number of occupants an emergency shelter can safely accommodate based on floor area, sleeping arrangement type, and applicable safety standards (SPHERE/FEMA guidelines).
Formulas Used
Net Sleeping Area:
Net Area (m²) = Total Floor Area × (1 − Common Area %)
Space-Based Capacity:
Cspace = ⌊ (Net Area ÷ Space Standard) × Sleeping Multiplier ⌋
Exit-Based Capacity (Egress):
Cexit = Number of Exits × Max Persons Per Exit
Final Safe Capacity:
Cfinal = min(Cspace, Cexit)
Sleeping Multipliers: Floor Mats = 1.0 | Cots = 0.9 | Bunk Beds = 1.8 | Family Units = 0.75
Sanitation (SPHERE): 1 toilet per 20 persons
Water (SPHERE): 15 L per person per day
Assumptions & References
- SPHERE Handbook (2018): Minimum 3.5 m² covered floor area per person in collective shelters; 1 toilet per 20 persons; 15 L water/person/day.
- FEMA P-361 / IS-120: 2.8 m² (30 sq ft) per person as a working standard for mass care shelters in the United States.
- Minimum Emergency Standard: 2.0 m² per person — used only in acute crisis phases; not recommended for stays exceeding 72 hours.
- Common areas (corridors, bathrooms, kitchen, registration) typically consume 20–35% of total floor area.
- Bunk beds increase sleeping density but do not reduce the per-person space standard for health and safety purposes; the multiplier reflects physical sleeping spots per unit area.
- Exit capacity is governed by local fire codes; the default of 50 persons per exit aligns with IBC (International Building Code) guidelines for assembly occupancies.
- This calculator provides planning estimates only. Final capacity must be verified by a licensed engineer and local emergency management authority.