What is luminous flux (LUMEN)? Led luminous flux formula

The current types of LED lighting now have different specifications, so when buying LEDs, you need to grasp the basic knowledge of these parameters to buy accordingly.

When buying a LED in general or solar LEDs in particular, you will see the parameters on the product, some common and important parameters of LEDs are Lumen, also known as optical. information. This is a factor when buying a lamp, you need to pay attention to make a decision to choose a suitable LED lamp for your living space.

So to help you understand more about this indicator, in this article Givasolar will share related information: what is luminous flux? Find out about the luminous flux of the LEDs, the calculation formula as well as the appropriate selection.

1. What is luminous flux?

Definition: Luminous flux (lumen symbol) is a photometric quantity that tells you the radiant power of a light beam emitted by a point light source. Or more understandably, it is the total amount of light emitted by a light source.

  • Unit of luminous flux (in SI, CGS units): lumen
  • Symbol of luminous flux: lm

Because the luminous flux indicates the brightness level of the light source when buying LEDs you should pay attention to the luminous flux index. If you want high brightness, choose LEDs with large luminous flux and vice versa. Or if you choose a lamp with a small luminous flux, more lights will be needed to light it up.

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2. The luminous flux of LEDs:

The luminous flux of the emitted LEDs is measured in lumens (lm). If you want intense lighting, choose lamps with a high lumen index. If you want to save energy or use lamps with a low lumen output, at least have enough illumination.

LEDs today are quite diverse. For example, ceiling recessed led lights to have common luminous flux at 600 – 1600Lm, luminous flux LEDs from 700-2000 Lm … Based on the luminous flux index on the lamp, the designer and construction of the light are easy to calculate the position of the lamp, the distance of the lamp, the appropriate number to ensure adequate light supply.

3. Why do you need to pay attention to the luminous flux index of the LEDs:

In the past, when using traditional lighting equipment such as incandescent and fluorescent lamps, people often paid attention to wattage (W) and assumed that a lamp with a large wattage was associated with a higher level of illumination. This is really not true for some other lamps such as chandeliers, wall lamps, table lamps, ceiling lamps or floor lamps, … using current LED technology. In fact, the amount of light emitted from a bulb is measured in lumens of luminous flux, not watts of power.

Lumens let you know how much light you need. So when buying LED bulbs, you need to care about lumens, not watts

With the outstanding advantages of lighting, it does not consume too much power and heat, and LEDs are extremely durable and have a long life, limiting costs in repairing and replacing bulbs. LED lights such as LED ceiling lights, led spotlights, led strip lights, table lamps, led wall lights, … are commonly used in home interior and exterior design. And most of all, solar-led light is the most optimal outdoor lighting device.

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How to convert watts to lumens?

Watt Incandescent
Halogenlumen CFLlumen LEDlumen
15W 90 120 125 135
25W 220 215 230 250
40W 415 410 430 470
60W 710 700 740 800
75W 935 920 970 1055
100W 1340 1320 1400 1520
150W 2160 2140 2250 2450

4. How to choose the lighting efficiency of LEDs with the luminous flux of LEDs?

Not just reference numbers. It also depends on a number of factors such as: the shape and size of the room, ceiling height, type of lamp, lighting area, color scheme, and user needs. Refer:

  • The kitchen and bedroom area has LED luminous flux from 300 – 400 lumens
  • The living room area has a lumen output of 400-500 lumens bathroom area with a lumen output of 500 – 600 lumens
  • The reading area has a luminous flux of 400 lumens
  • The area in the hallway had a luminous flux of 300 lumens
  • You should choose LEDs with lighting efficiency from 70 lumens / W – 90 lumens / W, with a luminous flux level of LEDs suitable for the lighting space in offices and houses.
  • For larger spaces such as stadiums, sports grounds, workshops, choose lighting efficiency from 100 lumens / W – 110 lumens / W.
  • For garden lights used as accent lighting, 50 lumens are usually sufficient for color and lighting in your yard.