Single beam and Dual Beam Headlight Bulbs

What’s the difference between Dual Beam and Single Beam headlight bulbs?

“Do I have dual-beam or single-beam headlight bulbs?” The answer to the question often brings confusion, but it’s surprisingly simple:

The term “Dual” and “Single” refer the function of a headlight bulb. A dual-beam headlight bulb has dual functions; The bulb creates a low and a high beam – “dual beams” in one headlight bulb. A single-beam headlight bulb has a single function; the one bulb creates only one beam (either low or high beam individually).


Dual Beam Headlight Bulbs
Dual Beam Headlight Bulbs have dual filaments which produce dual beam patterns: one bulb creates both high and low beam.
Dual Beam Headlight Bulbs
Since a dual beam headlight bulb can create dual beam patterns, only one bulb is needed per headlight housing. That one dual beam headlight bulb will create the high beam and the low beam.


Single Beam Headlight Bulbs
Single Beam Headlight Bulbs have one single filament inside the bulb which produces a single beam pattern: either high beam or low beam.
Single Beam Headlight Bulbs
Since a single beam headlight bulb can only create a single beam pattern, one bulb is needed for a high beam bulb and a second bulb is needed for a low beam bulb.

Just remember if you’re looking at an LED headlight bulb or HID conversion kit and you’re unsure of the difference, just remember to focus on the bulbs themselves, not the headlight housing. Do you have a bulb that does 2 beams in 1 bulb or 1 beam in 1 bulb?