[krsuresh]

What is lumen? Its relation with watt

[tkrussell]

Lumen:

Let me google that for you

Watt:

Let me google that for you

You will find that a lumen is a measurement of light, and that watt is a measurement of electric power, and there is no direct relationship between either.

[hermanwachs]

Light sources have widely varying efficencies for delivering light. Go here Bulbs at a Glance for information about lumens per watt.