The lumen (symbol: lm)

Lumen (lm) is used to quantify the total amount of visible light emitted by a light source. Lumen is a crucial metric when evaluating the brightness of light sources, especially when selecting lighting for various applications.

Luminous flux, measured in lumens, takes into account the entire spectrum of visible light as perceived by the human eye. This makes it a more accurate representation of how bright a light source appears to us compared to measurements based on other units like watts, which only indicate the amount of energy consumed.

Some context:

• Incandescent Bulbs: A typical 60-watt incandescent bulb produces around 800 lumens of light.
• LED Bulbs: LED technology has allowed for more efficient light production. An LED lamp with a power consumption of around 8-10 watts can emit the same amount of light (800 lumens) as a traditional 60-watt incandescent bulb.
• Light Fixture Labels: When you purchase light bulbs or fixtures, you'll often find information about their lumen output on the packaging. This helps you choose the right level of brightness for your needs.
• Illumination Requirements: Different tasks and environments require different levels of illumination. For example, reading may require higher lumens than ambient lighting.

Remember that while lumens indicate the brightness of a light source, other factors like color temperature (measured in Kelvin) also play a role in how the light appears and its suitability for a particular use.