How to use the required elevator count calculator
There is no United States code that tells you how many passenger elevators a building must have. The International Building Code regulates fire service access elevators in high rises, accessible means of egress and car size for emergency medical stretchers, but the number of cars is a design decision rather than a legal minimum. In practice it comes from a traffic analysis, and that is what this tool performs.
The method is the classic up peak calculation. Demand is the building population multiplied by the target five minute handling capacity, typically 11 to 15 percent for a single tenant office, 8 to 12 percent for multi tenant, and lower for residential buildings. One car moves 300 divided by the round trip time trips every five minutes, and each trip carries about 80 percent of rated capacity because passengers rarely fill a car completely. Dividing demand by that figure gives the number of cars.
Round trip time depends on travel distance, door times and the number of stops, so use 90 to 110 seconds for buildings up to about ten floors, 110 to 130 for mid rise and 130 to 160 for high rise until a consultant runs a simulation. The average interval, round trip time divided by the number of cars, is the quality check: 30 seconds or less reads as good office service. Confirm the final count and the code driven fire service and accessibility requirements with an elevator consultant and the design team.
Frequently asked questions
No. The IBC requires fire service access elevators in high rise buildings and elevators serving accessible routes, but it does not set a passenger count. The number of cars comes from traffic analysis and owner service targets.
For offices, divide the usable area by a density of roughly 150 to 250 square feet per person, or use the tenant headcount when it is known. Residential buildings are usually estimated from unit count and average household size.