Understanding the Difference Between Luminous Flux and Lumens

In an incandescent lamp, the current passes through the filament inside the bulb to generate heat and brightness. However, the heat accounts for a large proportion of the energy consumed, which is not what we need. In traditional lamps such as incandescent and fluorescent lamps, the higher the wattage, the higher the brightness, making wattage a measure of brightness at one time. When buying lights in the past, people would often look at the wattage of the bulb to determine if it was suitable for their needs.

For instance, we might need a 100W incandescent lamp to light up our living room. However, watts only measure the energy consumed by lighting fixtures and do not indicate how much light is produced. This is where lumens come in - they measure the amount of light produced by an LED fixture, allowing you to compare the brightness of different fixtures under the same usage conditions.

The key difference between wattage and lumens lies in their definition. Wattage measures the energy required by a light fixture to produce a certain amount of light, while lumens measure how much light is actually produced by the fixture. This means that a higher wattage does not always mean a brighter light.

In fact, LEDs have become popular in recent years because they can produce the required amount of light at a lower wattage (energy consumption). Knowing the difference between wattage and lumens, as well as calculated lux, can help you choose the right fixture for your application. Lux is the lighting effect achieved by the lamp after installation.

To convert watts to lumens, you need to know the luminous efficacy of the light source. For example, a 10W LED street light with a luminous efficacy of 100 lm/W would produce 1000 lumens (10W x 100 lm/W). You can then calculate the lux by dividing the lumens by the surface area.

In conclusion, understanding the difference between luminous flux and lumens is crucial when shopping for light fixtures. By knowing how to convert watts to lumens and finally from lumens to lux, you can choose the right fixture for your application and ensure optimal lighting performance.

Luminous flux to lumens