Luminous Flux vs. Lumens: Know its Difference!

Basically the lumens is the unit radiated from luminous flux! They are measure of total amount of visible light  to the human eye from a light source or lamp.

luminous flux-energy radiate-unit is lumens

Luminous Flux (ø)


Luminous flux is the quantity of the energy of the light emitted per second in all directions. The unit of luminous flux is lumen (lm).


In other words, it is the quantity characteristic of radiant flux which expresses its capacity to produce visual sensation evaluated according to the values of relative luminous efficiency for the light adapted eye:

a) Effective luminous flux (øn)Total luminous flux which reaches the working plane.

b) Nominal luminous flux (ø0) Total luminous flux of the light sources in the interior.

Lumens  are denoted by lm are a measure of the total amount of visible light  to the human eye from a light source or lamp. The higher the lumen rating the “brighter” the lamp will appear or we can say the more lumens in a light bulb, the light is brighter.


In other words, it is SI unit of luminous flux. The luminous flux emitted within unit solid angle (one steradian) by a point source having a uniform intensity of one candela.

Lumens used in house depends on a number of factors including; room size and shape, ceiling height, colour scheme or interior, type of lamps & fitting , task areas and needs of the user. As a general guide; below are the lumens required for different room settings per 10 sq ft. In many cases a mixture of general and task lighting will be required.

Living room400 – 500
Kitchen300 – 400
Kitchen (Task)700 – 800
Bedroom300 – 400
Bedroom (Task)700 – 800
Bathroom500 – 600
Bathroom (Task)700 – 800
Reading area400

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