Luminous Efficacy Calculator
Calculate and compare the energy efficiency of different light sources. Measure lumens per watt and estimate annual energy costs.
1Light Source Parameters
Total luminous flux from the light source
Total power draw including driver losses
Energy Cost Settings
2Efficacy Results
80
lm/W
Compared to typical LED Standard
Daily Energy
0.08 kWh
Annual Energy
29.2 kWh
Energy Cost Analysis
Potential savings with premium LED upgrade:
Save $1.64/year
Equivalent Wattages
Power needed to produce 800 lumens
Efficacy Rating Guide (lm/W)
Why Luminous Efficacy Matters
Luminous efficacy (lm/W) measures how efficiently a light source converts electrical power into visible light. Higher efficacy means more light per watt of electricity, resulting in lower energy costs and reduced environmental impact. Modern LED technology has dramatically improved efficacy compared to traditional lighting.
How to Use This Calculator
Enter the total lumen output and wattage of your light source. The calculator determines the efficacy in lumens per watt (lm/W) and compares it against typical values for different light source types. It also estimates your annual energy costs and potential savings from upgrading to more efficient lighting.
Energy Efficiency Tips
- •Premium LEDs achieve 150+ lm/W efficacy, nearly 10x better than incandescent bulbs
- •Include driver/ballast losses when calculating total system efficacy
- •Higher efficacy often correlates with better thermal management and longer lifespan
- •Consider the total cost of ownership including energy costs, not just initial purchase price