Watts to Lumens Online Calculator

This online calculator estimates light output in lumens (lm) based on power consumption in watts (W) and bulb type. It supports LED, CFL, halogen, and incandescent lighting.

How to Use This Tool

• Enter the power value in watts into the input field.
• Select the bulb type from the dropdown:
  • LED – highly efficient (90 lumens per watt)
  • CFL – compact fluorescent lamp (55 lm/W)
  • Halogen – moderately efficient (20 lm/W)
  • Incandescent – lowest efficiency (15 lm/W)
• Click the Convert button to calculate estimated lumens.
• The result will be shown in the “Result in Lumens” field.
• You can adjust decimal precision using the “Decimal Places” input.
• Use the Copy Result button to copy the output.
• Clear All resets all inputs and results.
• Swap opens the reverse calculator: Lumens to Watts.

Definitions of Measurement Units

Watt (W)

The watt is the SI unit of power, representing the rate of energy usage or transfer. Abbreviation: W. 1 watt equals 1 joule per second. In lighting, it measures how much electrical energy a bulb consumes. For example, a 10W LED bulb uses 10 joules of energy per second. 1 W = 1000 milliwatts (mW). There is no direct imperial power unit; however, horsepower (hp) is used in mechanical contexts, where 1 hp ≈ 746 W.

Lumen (lm)

The lumen is the SI unit of luminous flux, measuring the total quantity of visible light emitted by a source. Abbreviation: lm. It quantifies brightness perceived by the human eye. The higher the lumen value, the brighter the light. 1 lumen ≈ light output from 1/683 watt of radiant energy at 555 nm wavelength. It has no direct imperial equivalent and is specific to photometric systems.

Watts to Lumens Chart by Bulb Type

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