LED Power Calculator
Calculate LED power consumption, efficacy and the running cost of a lighting installation.
About LED Power Calculator
Efficacy is the figure that matters when comparing fittings: modern LEDs reach 100 to 150 lm/W against about 15 lm/W for incandescent. Running cost follows directly from total power and hours. Lighting often runs 10 hours a day or more, so efficacy differences compound into large annual savings even at modest installed power.
Formula
LED Power
Efficacy = lumens ÷ watts; annual energy = total watts × hours × 365 ÷ 1,000
- efficacy
- Light output per watt, the measure of lighting efficiency
Worked example
With the default values below, LED Power Calculator returns Total Power of 480.00. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Number of LEDs or fittingsminimum 0
- 40
- Power per fittingminimum 0 W
- 12 W
- Light output per fittingminimum 0 lm
- 1,400 lm
- Hours per dayaccepts 0–24 h
- 10 h
- Energy price per kWhminimum 0
- 0.15
Results
- Total Power
- 480.00 W
- Total Light Output
- 56,000 lm
- Luminous Efficacy
- 116.67 lm/W
- Annual Energy
- 1,752.0 kWh
- Annual Running Cost
- $262.80
Step by step
- 1Values used
- 2LED Power
- 3Total Power= 480.00 W
- 4Total Light Output= 56,000 lm
- 5Luminous Efficacy= 116.67 lm/W
- 6Annual Energy= 1,752.0 kWh
- 7Annual Running Cost= 262.80
Assumptions and limits
- The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is LED Power calculated?
Efficacy = lumens ÷ watts; annual energy = total watts × hours × 365 ÷ 1,000 Efficacy is the figure that matters when comparing fittings: modern LEDs reach 100 to 150 lm/W against about 15 lm/W for incandescent. Running cost follows directly from total power and hours.
Why does LED Power matter?
Lighting often runs 10 hours a day or more, so efficacy differences compound into large annual savings even at modest installed power.
What values do I need to enter?
This calculator takes 5 inputs: Number of LEDs or fittings, Power per fitting, Light output per fitting, Hours per day, Energy price per kWh. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.