How to convert watts to lumens

How to convert electric power in watts (W) to luminous flux in lumens (lm).

You can calculate lumens from watts and luminous efficacy.  Watt and lumen units represent different quantities, so you can't convert watts to lumens.

Watts to lumens calculation formula

The luminous flux ϕ_V in lumens (lm) is equal to the power P in watts (W), times the luminous efficacy η in lumens per watt (lm/W):

ϕ_V(lm) = P_(W) × η_(lm/W)

So

lumens = watts × (lumens per watt)

or

lm = W × (lm/W)

Example

What is the luminous flux of a lamp that has power consumption of 60 watts and luminous efficacy of 15 lumens per watt?

ϕ_V = 60W × 15lm/W = 900lm

Luminous efficacy table

Light type	Typical luminous efficacy (lumens/watt)
Tungsten incandescent light bulb	12.5-17.5 lm/W
Halogen lamp	16-24 lm/W
Fluorescent lamp	45-75 lm/W
LED lamp	30-90 lm/W
Metal halide lamp	75-100 lm/W
High pressure sodium vapor lamp	85-150 lm/W
Low pressure sodium vapor lamp	100-200 lm/W
Mercury vapor lamp	35-65 lm/W

 

How to convert lumens to watts ►

 

---

See also

• Watts to lumens calculator
• How to convert lumens to watts
• Lumens to lux calculation
• Lux to lumens calculation
• Watts (W)
• Electrical calculation
• Power conversion
• Energy conversion