Light Output: Lumens

The lumen (symbol: lm) is the SI-derived unit of luminous flux, a measure of the total quantity of visible light emitted by a source per unit of time. Luminous flux differs from power (radiant flux) in that radiant flux includes all electromagnetic waves emitted, while luminous flux is weighted according to a model (a "luminosity function") of the human eye's sensitivity to various wavelengths. Lumens are related to lux in that one lux is one lumen per square meter ...

... Lamps used for lighting are commonly labelled with their light output in lumens; in many jurisdictions this is required by law.

A 23 W spiral compact fluorescent lamp emits about 1,400–1,600 lm. Many compact fluorescent lamps and other alternative light sources are labelled as being equivalent to an incandescent bulb with a specific power. Below is a table that shows typical luminous flux for common incandescent bulbs and their equivalents 

 From Wikipedia - The Free Encyclopedia

Is Luminous Flux the same as Lumens?

...In photometry, luminous flux or luminous power is the measure of the perceived power of light. It differs from radiant flux, the measure of the total power of electromagnetic radiation (including infrared, ultraviolet, and visible light), in that luminous flux is adjusted to reflect the varying sensitivity of the human eye to different wavelengths of light

...The SI unit of luminous flux is the lumen (lm). One lumen is defined as the luminous flux of light produced by a light source that emits one candela of luminous intensity over a solid angle of one steradian. In other systems of units, luminous flux may have units of power...

1 Lm = 1 cd x 1 sr

 From Wikipedia - The Free Encyclopedia