DSLRUsers.com

I am looking at several led light options. Obviously, one of the considerations is how much light the led panel emits.
Some companies list their products specifying out put via "lux"
http://www.adorama.com/fpvl500c.html
Others list Watt, W.
http://ikancorp.com/productdetail.php?id=998
Others use lumens...

My questions: How to measure/compare the lighting output of led lights? Is there a way to convert these numbers? All I want to know how much light these lights output so I can compare them.

Watts measure the amount of power the device uses. It has no direct bearing on the light output as other factors like efficiency come into play. It is mainly used as a comparison to old tungsten lighting to say "Look how good we are"

Lux is the the measure of the light output of the device and is the correct figure to use in this instance

Lumens is the amount of light illuminating the subject, and while this is the figure you should be most interested in, it has no relevance to a lamp sitting in a box on the shelf in a store. It is dependent on distance to subject, albedo of subject and angle of spread of the output.

To convert Lumens to Lux (or vice versa) try this: https://www.ledrise.com/shop_content.php?coID=19

You should also be interested in the CRI figure. This is an indicator of the quality of the light. It should be as close to 100 as you can get.