Free Lighting Layout Calculator
Determine the number of light fixtures needed for a room using the lumen method and desired foot-candle level.
ft
ft
fc
lm
Fixtures Needed
0
Total Lumens Required15,000 lm
Estimated Wattage (LED)0 W
Fixtures Needed vs Room Length
Lumen Method for Lighting Design
N = (Area x FC) / (Lumens per Fixture x CU x MF)
Where FC is the target foot-candle level, CU is the coefficient of utilization (depends on room shape and reflectance), and MF is the maintenance factor (accounts for dirt and lamp aging).
Example Calculation
20x15 ft office at 50 fc using 3,200-lumen fixtures, CU=0.6, MF=0.8.
- 01Area = 20 x 15 = 300 sq ft
- 02Lumens needed = 300 x 50 = 15,000 lm
- 03Effective per fixture = 3200 x 0.6 x 0.8 = 1,536 lm
- 04Fixtures = 15,000 / 1,536 = 9.77, round up to 10
Frequently Asked Questions
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