Lumen is the SI derived unit measuring how much light you are getting from a bulb.

While watt is a unit of power measuring the amount of energy an item needs to function.

**Formula to convert W to lm.**

Converting these units is like measuring how well a light source converts energy into light.

For a 100 W incandescent bulb produces about 1,600 lumens, for an efficiency of 1,600/100 = 16 lumens per watt.

A halogen bulb consumes only 72 watts for the same amount of brightness, making its efficiency to be 22 lumens per watt.

A CFL bulb consumes 26 W making its efficiency to be 61 lumens per watt.

LED bulbs, which are the most efficient, consume only 22 watts for an efficiency of 73 lumens per watt.

**Example:**

Convert 75 watts incandescent bulb if its efficiency is 15 watts per lumen and you asked to convert the energy to lumens per watt.

**= 75 x 15**

**=1125 Lumens.**

**= 800 lumens.**