Lighting Layout Calculator

Calculate number of fixtures needed using the lumen method (zonal cavity).

Room Length (ft)

Room Width (ft)

Mounting Height (ft) Floor to luminaire

Work Plane Height (ft) Typically 2.5 ft (desk height)

Space Type / Target Foot-Candles

Target Foot-Candles

Lumens per Fixture

Fixture Type

Coefficient of Utilization (CU) Typical: 0.5-0.8

Light Loss Factor (LLF) Typical: 0.7-0.9


                            N = (FC x Area) / (Lumens x CU x LLF)


                            RCR = 5h x (L + W) / (L x W)

IES Recommended Lighting Levels

Space Type	Foot-Candles	Lux	Notes
Corridors/Hallways	5-10	50-100	Basic circulation areas
Storage/Warehouse	10-30	100-300	Inactive storage
General Office	30-50	300-500	Computer work, reading
Classroom	50-75	500-750	Reading and writing tasks
Retail/Showroom	50-100	500-1000	Merchandise display
Detailed Work	75-100	750-1000	Drafting, accounting
Manufacturing	50-100	500-1000	General assembly
Fine Assembly/Inspection	100-200	1000-2000	Electronics, quality control