Lumens are an integral part of LED technology. But what exactly are they? How do they work, and why are they important?

If you’ve found yourself asking these questions, then you’re in the right place. We’re going to explain everything you need to know about lumens to get the best light upgrade possible. Keep reading for all the info on what lumens are.


So what are lumens? Put simply, lumens are used as a measurement of how much visible light (to humans) is emitted from a light source. They’re often marked by the abbreviation lm, similar to cm for centimeters or in for inches. The larger the lumen value, the brighter the light source is to humans.

A common misconception is that power consumption measured in Watts measures light output. Generally, a 60w light will be brighter than a 40w one — but that’s because the extra power often gives a higher lumen value, not because of the watts themselves. It’s possible for a 60w lamp to be dimmer than a 40w one if it’s less efficient in its power usage. This is particularly relevant when discussing LEDs.

LED Power Efficiency

Now that we’ve explained what lumens are, we can cover why LEDs offer superior lumen values at lower wattage. LED lights are designed to be incredibly power efficient compared to traditional halogen lights. A 6.5w LED light can have the same lumen measurement, around 600lm, as a 50w halogen light. That’s nearly a 10x increase in power efficiency.

And, as technology improves, lumens in LED lights get better and better. If you ever need help remembering the comparison, many LED light packages will label the lumen value on the box. They may even have a comparison to conventional watt values.

Useful Lumens

Lights on the freeway at night

Beyond what lumens are, some lumen values can be somewhat misleading. Non-directional bulbs (circular bulbs that emit light in all directions) calculate the lumen output for all directions. For these lights, this is accurate, since light is going in every direction. However, headlights, which only use a cutout dome of the light space, still calculate the lumen value for all directions, even when they’re not used.

Some areas have implemented a useful lumen rating which only calculates the visible lumens of the light. If it’s not listed, just remember that headlights won’t use all of the lumens as listed. Often it will be a 90-degree cone, or between 1/4th and 1/3rd of the total lumen rating.

What do you need?

Now that you know what lumens are, you need to figure out how many lumens you need. If you often drive through areas that have some ambient lighting through streetlights, then you likely don’t need as many lumens in your LED lights. If you’re going through isolated areas without any lighting, however, then you’ll want something brighter. If you have absolutely no idea, then a good rule of thumb is to check the current lumens on your headlights, and go for LEDs 100-200 lumens brighter.

If you’re at all confused or need help with figuring out your lumens, contact us. Get increased brightness and helpful DIY guides for your car with PrecisionLED.