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How to Pick the Right Light Bulb Size for your Car

As a car owner, you need to know the ins and outs of your vehicle and what better way to start than to learn all about automotive headlight bulb sizes. The following guide will help you get a better understanding of the different aspects related to car headlights, and also how you can replace one on your own.

Knowing your Car’s Light Bulb Code

Different Sizes Of BulbsWhen you start looking for a headlight bulb for your car, the first thing you will need to do is to consult your car’s manual. This will ensure that you will get the right kind of bulb, be it a halogen bulb, HID or an LED light bulb.

Once you’ve seen your car’s headlight, you will see that these bulbs come in various sizes. Each of these headlight bulb sizes is represented with number and letter combination.

These combinations of letters and numbers are codes provided by the United Nations in order to standardize the bulbs in different countries. This means that even if you live in the United States and you own a Japanese car, you can rest assured that whatever bulb you buy from Amazon remains in line with the United Nations safety regulation.

According to the United Nations Regulation No. 37, a document which tackles the regulation of headlamps, there are three main categories of headlamps:

  • Group 1: Headlamps without general restrictions.
  • Group 2: Car lamps which are to be used only as signalling lamps, cornering lamps, reversing lamps and rear registration plate lamps.
  • Group 3: Headlamps which are to be used only for replacement of lamps in older car models.

If you notice, these headlights’ codes are usually starting with an H, P, or S. But don’t panic! H in these headlights stand for Halogen, P and S are codes in headlights to mean that they are LED light bulbs.

What are the Different Kinds of Headlight Bulbs to Choose From?

The following 3 headlight bulbs are the most sought-after types in today’s market:

  • The Halogen Bulb- This type has been around for the longest time period and dates back to the 1960s. The halogen bulbs emit more light than the traditional ones by consuming the same power. The efficiency of Halogen bulbs can be attributed to their mechanism. Halogen bulbs contain a highly reactive halogen gas that helps the tungsten filament burn even brighter than a normal light bulb making them effective as headlights.
  • The HID/Xenon Bulb- World-famous company, Philips, launched the HID or High-Intensity Discharge bulbs as an improvement to the halogen bulbs. These bulbs don’t work on burning filament, but instead use a light arc placed between the two electrodes situated inside a chamber filled with xenon gas. This arc is made up of ionized xenon, which produces a current between the electrodes, thereby emitting a blueish bright light.

What Kinds of Options Does Someone Have When Picking Bulbs?The luminous efficacy of these lights is better than the halogen bulbs, which increase the visible spectrum. This means that you can see better with the Xenon bulbs as they produce better incandescence than a halogen bulb.

And since there are no filaments to burn, these bulbs last longer than the halogen bulbs. However, they require more power than halogen or LED bulbs, and the glare produced by these bulbs is too powerful. That is why you may require fitting in beam leveling control (automatic) and lens cleaning system to avoid any untoward incident while using these bulbs on road.

  • The LED bulb- The LED or Light Emitting Diodes bulbs do not wear and tear like the Xenon or halogen bulbs. The durability of the LED bulbs can last a lifetime, and certain manufacturers claim durability of up to 30,000 hours. They require very little power as against the two other headlight bulb types. In terms of light intensity emitted by LED bulbs, it is considered to be higher than HID or Halogen bulbs. The light is crisp and white, somewhat like daylight, thereby offering maximum illumination with fewer glares.

Why are there Different Sizes of Light Bulbs?

  • Bulbs aren’t “one-size-fits-all”- No car is designed identically and this goes the same for all the available light bulbs in the market today. Light bulbs vary in order to help motorists see better and more comfortably especially at night. Knowing about your car’s light bulb size will ensure that it will fit perfectly in your car’s headlight socket for safer driving.
  • Bulb Design- Another reason for the difference in size of the bulbs is their build. There are some bulbs that use a single filament, while there are others that come with double filaments. Double filaments are commonly seen in bulbs known to produce both high or low beam. Single filament or single beam headlights only produce either high or just a low beam.
  • Dimension Difference- Bulbs come in various dimensions which implies that the headlight space design will dictate what kind of bulb you should buy. Choose the one that is sized properly to fit into the headlight space. To check for the right size and conversion, refer to your car’s manual always.

Different Sizes Of Bulb

Most Popular Sizes Used in Vehicles Today

Some of the most popular headlight bulb sizes used in modern day vehicles include the following: H1, 207, H6W, 233, H3, 239, 245, H3C, H4, H15, H13, 380, HB3, 382, H1R2, H7, HB4, H8, H9, H11, HB4A.

All the major brands offer headlight bulbs in these sizes, which you can use either for replacing your old headlight bulb or upgrading your current bulbs.

Do-it-Yourself Headlight Bulb Replacement

We cannot emphasize this more than enough, that before you start thinking about replacing your car’s headlights, you should begin by doing the most basic and that is by checking your car’s manual to learn about the correct type of headlight to buy and also to know how to properly change it.

Once you have purchased the right headlight bulb, you can proceed with the following steps:

  • Step no.1- Make sure that the car is not switched on. Turn off the engine and remove the keys from the ignition. By doing so, you are ensuring your safety and your car’s.
  • Step no. 2- Open your car’s good and look for the headlight holder just close to the front end of your vehicle.
  • Step no.3-  Once open, you will see that there is a cap or a clip that holds the headlight bulb, you can push down this cap or clip to further open it.
  • Step no. 4- Carefully loosen up the existing headlight bulb. DO NOT JUST YANK IT OUT OF THE SOCKET! Do this carefully because these bulbs are fragile and you might risk injuring yourself if not done carefully. Also, some cars have kept the light bulb socket/holder just in the inner fender and you will have to move past the air filter housing to reach it. Do this carefully, otherwise, you will have to replace the whole socket should you break it.
  • Step no. 5- Screw the new bulb into place carefully. Make sure that your hands are clean and free from oil or grease. These bulbs are gentle and can burst open in case it gets heated up with oil on the surface.

Popular Sizes Used in Vehicles Today

NOTE: has an excellent article that will let you learn more information about appropriately replacing bulbs on any automobile.


Hopefully, now you have a clearer picture about headlight bulb varieties, sizes, and simple steps to install a headlight.

We would like to stress that picking the right size of a headlight bulb is the key to a successful installation of a new headlight bulb to upgrade your vehicle.

If you’re still looking for an even better option for a brighter night driving, we have a buyer’s guide on LED bulbs for your car. Currently, LED outweighs the old halogen bulbs in terms of illumination.

Ever changed your car’s headlight bulbs yourself? Do comment below and let’s grow our community of well-informed buyers only here on!


1 Comment

  1. simplecarguy39 Reply

    ive worked in garages all my life and one thing that irritates me is just how some of those handy mannies out there always, and when i say always, make a mistake with their headlights. they complain about how the headlights just stopped working altogether when the bulbs weren’t right in the first place. before you even go about “upgrading” your headlights besure to read your car manual forchrissakes! save your ass alot of money. That said you forgot one of the most important tips. If you can’t install it on your own or if you are having doubts, bring it in your local car garage. They will have all the tools and all the parts to replace your car. even though you’ve had that car for years, nothing can beat expert knowledge when it comes to something technical. even for something so small as changing your car’s headlights.

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