Difference Between LUX and LM—Important Information for buyers, especially for them when buying lights for government projects.
What’s the difference between LUX and LM? Is it 1LUX=1LM?
Answer: No. 1LUX≠1LM.
One customer complained about that supplier’s documents do not match the real situation, he said, “lumens of LED Chips was 170LM/W, but why LUX was only half of it?” That’s a good question, and it is a professional question as well.
First, Let us learn about what are Lux and Lm.
- Lumen means Light source radiates into the surrounding space in unit time and cause the vision of the energy. It is denoted by Φ, unit: Lm.
- The luminous flux received per unit area is called illuminance, it is denoted by E, unit: lux (Lx).
Second, let us learn their relationships from a formula:
- E=Φ/S
- E-LUX, Φ-LM, S-㎡ (The illuminated area)
And their conversion relationships as bellow:
- 1 lux =1 lumen Light flux evenly distributes over an area of 1 ㎡
- 1 lumen = the luminous flux emitted per unit solid Angle from a point source with an emission intensity of 1 candela
- 1 lux = illuminance on a sphere with a radius of 1m generated by a point source with an emission intensity of 1 candela
When customer using Lux meter to test the LUX for lights, please pay attention to that it will be affected by testing angle and distance, and then to test LUX according to the user manual.
OK, back to the question of the customer, we suggest to test it both before installation and after installation for the lights, and the data of after installation is what we are requested. Anyway, lux is just a data, lighting effect is the most important aspect for users, some lights with very high lux close to the led chips, but actually it is with really dim lighting on the road, so LUX is not the only referent point for lighting effect, buyers should consider more for the specifications of lights, the most simple way is to take a sample to install and then test it, and it is the most guaranteed way for customers too.
Editor: Chloe, www.topmeid.com, ledsolarlight@topmeid.com
