Convert Watts to Lux

This Watts to Lux Calculator converts electrical power into illuminance. Enter watts, luminous efficacy, and area to instantly see the lux value.

How to Convert Watts to Lux

To understand the calculation, you first need to know the units:

• Watt (W): Measures electrical power consumption.
• Lux (lx): Measures illuminance, or the amount of light per unit area (lumens per square meter).

The formula for converting watts to lux is:

Lux = (Watts × Luminous Efficacy) ÷ Area

Where:

• Watts is the total electrical power used.
• Luminous Efficacy is how many lumens your light source produces per watt (lm/W).
• Area is the surface being lit, in square meters.

💡 Example:
If you have a 20-watt LED lamp with an efficacy of 100 lm/W lighting a 5 m² area:

Lux = (20 × 100) ÷ 5 = 400 lux

Lux to Watts Calculator

Common Watts to Lux Conversions

Below are some quick examples assuming Luminous Efficacy = 100 lm/W and Area = 1 m²:

• 1 watt → 100 lux
• 5 watts → 500 lux
• 10 watts → 1000 lux
• 20 watts → 2000 lux
• 50 watts → 5000 lux
• 100 watts → 10,000 lux

Watts to Lux Chart

Here’s a watts to lux chart you can use for quick reference (based on 100 lm/W, 1 m² area):

Note: The actual lux will vary depending on your light source’s efficiency and the size of the illuminated area. Use the calculator above to get precise results for your setup.