Here's Why Some LED Headlights Work And Others Just Blind Everybody

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Screenshot: Headlight Revolution, Image: Andrew P Collins

LED technology has come a long way in the last five years, and in 2020 there are a bunch of brands selling well-made, well-engineered LED replacements for your car’s old halogen headlight bulbs. Here’s how to figure out which ones to get.

(Full Disclosure: Be careful when modifying your car, especially with anything safety-related, like headlights, as not all aftermarket products are going to be road legal. Do your own research and mod at your own risk!) 

The appeal of LED headlight “bulbs” is simple: Increased light output for better nighttime visibility. And lower power draw. And! They make an old car look more modern. But if you buy a pair, it’s critical to understand that more LEDs do not equal better light. In fact, the good LED bulb replacements actually have fewer diodes.


(Just to be clear, we’re talking about aftermarket LED retrofits where you swap halogen headlight bulbs for plug-and-play LEDs and don’t mess with the factory headlight housing otherwise.)


If you’re going to use an LED bulb replacement in a standard reflector headlight housing, you want one with the light chips that install in exactly the same position that a halogen bulb’s filament would be.


LED bulbs with a multi-sided barrage of diodes look like they’d provide more light, but all they really do is blind oncoming traffic.

When you buy the right bulb, make sure it’s installed correctly!


For a long time I was staunchly against LED retrofits and I always advised people to just run high-performance halogen bulbs if they wanted the best lighting in older vehicles with stock reflector light housings.


However, technology has improved since I did my first LED-vs-halogen comparison test in 2015 and so has my understanding of light science. For that, I have to shoutout Chris Nelson at Headlight Revolution. That’s an online headlight bulb store that also has an informative YouTube channel illustrating the finer points of modern headlight mods.

I don’t know them personally and have no professional affiliation, but wanted to share this new HR video because it does such a great job showcasing why LED bulb replacements bristling with diodes are actually crap. The ones you want use fewer, more tactically placed, diodes.



The headlight housing in most older cars has a bunch of reflectors surrounding a halogen bulb. A halogen bulb, as you’ve probably seen, works like any other old-school light bulb in your house: Electricity goes through a little filament in the middle and light comes out from all angles.


Except, it doesn’t really come out from all angles. It comes from the filament I just mentioned. And when your headlight was designed, the reflectors were positioned just-so so that they’d bounce the light from said filament down the road without blinding other drivers. The focus is key. It doesn’t matter how bright a light bulb is if it’s just scattered and blasting light every-which-way.

So now we come to the news you can use. When you’re looking for an LED bank to replace a halogen bulb, it makes sense that you’d want one with enough diodes to throw light in all directions just like a halogen bulb seems to, right? Intuitively, it seems like a many-sided LED bulb replacement would be the way to go.


But as we can see in Headlight Revolution’s video, that’s not how it ends up working. The “360-degree” or “omnidirectional” three and four-sided LED bulb replacements push a lot of light, just not where you need it.

“What we’re looking for is something that mimics the original halogen bulb, not something that creates a blinding wall of light,” Headlight Revolution host Chris Nelson explains.


Indeed. That’s why the dinkier-looking LED bulb replacements, with small light chips positioned exactly where the filament would be on a halogen bulb, are where it’s at.

Of course, you’re still going to want to look at a reputable brand and a well-made product for good lighting. But the positioning of the LED chips relative to the positioning of a filament on a halogen bulb is a good gauge of whether the LED bulb you’re looking at will shoot light effectively or just dazzle oncoming traffic.



One last critical note about swapping a halogen bulb for an LED: Make sure it’s installed correctly! If you pick an LED with the light chips in the right place but install it upside down (not hard to do) you’re going to be just as boned as if you bought the wrong bulb altogether.


Headlight Revolution actually happens to have a clip about that, too:

So if you want LEDs, make sure they match the halogens you’re replacing. Not only on the bench, but in your housing as well!