You might have heard or read a debate regarding the use of H4 vs. 9003 bulbs. Yet, believe it or not, they’re almost the same but a bit different legally.
Vehicle headlights are essential in our everyday travel. Due to the protection these bring, vehicle owners usually invest in upgrading and maintaining their headlights.
Fortunately, many brands offer a wide array of headlights suitable for various vehicles. These help you drive amid heavy rain, thick clouds of smoke or fog, or even widespread blackout.
For instance, many vehicle owners prefer the more popular and cheaper incandescent halogen bulbs with Tungsten filaments. On the other hand, some owners would choose stylish and long-lasting LED bulbs with a white-bluish light.
Meanwhile, some automobiles are compatible with the newer Xenon High-Intensity Discharge (HID) bulbs. These are considered a step-up from halogen bulbs due to their brighter lighting but shorter life spans than LEDs.
In terms of lighting, drivers may choose between single-filament and double-filament bulbs. Headlight bulbs also differ in their bases, with some having two prongs while others with three tips.
Yet, you can’t simply buy the headlights that you prefer. For one, compatibility is an issue since vehicles can only use headlights with a specific number of prongs in the bulb.
In addition, countries such as the United States (and individual states), United Kingdom, Canada, and the European Union have headlight laws. These laws require the use of headlights with distinct specifications and usage.
Compatibility, lighting, price, and legal considerations should be factored in as you plan to upgrade or replace your headlights.
It is especially the case for H4 and 9003 Bulbs which are often confused upon by vehicle owners. These are technically the same but differ in several features that are a big deal in regulations across countries.
What do we need to know about H4 and 9003 headlight bulbs? What are the features that set them apart from each other?
Lastly, which of these are best for our vehicles? Here’s our comparison of H4 and 9003 bulbs.
Comparing Headlight Bulbs H4 vs. 9003
Vehicle owners often confuse the H4 and 9003 bulbs. It’s understandable, as both bulbs look the same for their appearance and structure.
For one, the H4 and 9003 bulbs are both double filaments in nature. It means that the two bulbs can provide lighting for the vehicle’s main and dipped beams.
In addition, both bulbs are built with three tabs or rods on their base. But, one H4 rod is shorter than the other two rods, while the 9003 has three tips of equal length.
Does this matter? Yes, as H4 tabs are compatible for vehicles with H4 and 9003 housings, but the 9003 isn’t for an H4 outlet.
Another distinction between the two bulbs is the location and legal restrictions for each bulb. For this, let’s briefly look into the history of both bulbs and the current laws.
H4 bulbs first became popular in Europe in 1971. These bulbs are dual-beamed and are replaceable.
But, it did not catch on in the United States, as the country required sealed headlights in cars. Initially, U.S. law required the use of two headlights with a 7″ diameter but eventually changed for four 5¾”-diameter headlights.
Yet, it did catch on motorcycles as these do not require sealed lamps.
The U.S. Department of Transportation eventually permitted non-sealed headlights in cars in 1983. However, it was not until the early 90s when they standardized the HB2 or 9003 headlights for consumption.
Here’s the current provision on the use of 9003 headlights under S10.15.4.1.1 of the Federal Motor Vehicle Safety Standards (FMVSS) 108:
“No such markings are required if the light sources in the headlamp are any combination of dual filament light sources other than HB2.”
Meanwhile, other countries in Europe and different continents have been using the H4. Still, headlights should comply with national and local laws and regulations.
But, what exactly makes H4 and 9003 bulbs different from each other? Let’s break their features down.
According to United Nations Regulation No. 37, H4 Lamps has a rated voltage of 12V (60-55W) and 24V (75-70W). This bulb can perform as a headlight and brake light but not as a signaling light.
The H4 is considered a double-filament bulb intended for high and low beam light.
Additionally, this kind of headlight bulb has a three-prong base. But, the tabs on the bottom are uneven, with two tabs having equal lengths and one tab having a shorter length.
H4 has tungsten filaments as well, which makes it compatible with vehicles with traditional halogen headlights. Yet, modern H4 exists through LEDs that utilize light-emitting diodes (hence the name) to convert electricity to light energy.
Installing an H4 bulb in your vehicle is possible if the car or motorcycle supports a three-prong installation. Given the lengths of the rods, you should ensure that the vehicle supports H4 installation.
For most countries, H4 bulbs have been used favorably for headlights, including race cars. The United States uses a similar yet distinct type of H4, the HB2 or 9003 bulbs.
If you’re residing in a country that standardized the H4, you can use such bulbs for your vehicle. Yet, you should further check your country’s motor and traffic standards and vehicle specifications before purchasing an H4.
9003 or HB2 Bulbs are the same as the H4. Both are double-filament bulbs with a three-prong base.
But, the 9003 has some modifications from the original H4, such as the exact length of the tabs. According to the FMVSS 108, the rods should be measured at ½ inch in diameter.
If you look into the factsheets of 9003 bulbs online, you’ll notice how all of these operate at 12.8V. It is also a product of the U.S. standardization under the Federal Motor Safety Standard 108.
Given the design of the base, the 9003 is compatible with vehicles with 9003-compatible headlight mounts. This bulb does not support mounting at vehicles that use H4 headlights.
Nonetheless, installing the 9003 is just the same as installing the H4.
Much like the H4, 9003 bulbs are available in tungsten (halogen) and LED. But, there are also Xenon HID 9003 headlight bulbs in the market.
Are Xenon lights legal in the United States? According to Sgt. Neil Dickenson, Public Information Officer of the Minnesota State Patrol, if it complies with U.S. standards, then it’s legal.
But, Dickenson further made a distinction between manufacturer-based and over-the-counter Xenon headlights. He explained that, unlike manufactured lights that follow federal guidelines, those purchased on outside markets might’ve not complied with the law:
“The aftermarket use of xenon lights poses a more difficult problem. Most aftermarket systems are in compliance with SAE and federal standards. However, some “look-alike” systems are not. The vehicle lighting system in question would need to be inspected by a reputable mechanic. The bulbs should contain the proper markings to permit the lighting device to be traced back to the appropriate SAE standard. If they are not legal, a person can be issued a citation,” Dickinson said.
Vehicles traveling within the United States’ territory must comply with the provisions stated in S3.1 of the FMVSS 108. It includes motorcycles, private and commuter cars, buses, trailers (excluding converter dollies and pole trailers).
S3.3 of the law also covers replacements for headlamps and other accessories for the said vehicles under the said law.
In general, under the law, motorcycles, cars, buses, and trailers should comply with the use of the 9003 bulbs. Car manufacturers are also obliged to install 9003 bulbs that are marked “DOT HB2.”
Summary of Comparison
Historically, H4 and 9003 bulbs are quite the same. However, the 9003 bulbs are considered a slight modification of the H4, crafted for use within the United States.
While these two double-filament bulbs have three rods in their bases, the 9003 strayed away from H4’s uneven tabs. Instead, the 9003 uses three rods of equal lengths of ½ inch in diameter.
H4 is a more flexible incompatibility as it can operate on both H4 and 9003 headlight mounts. But, the same cannot be said for the 9003, which is only for 9003-compatible devices.
What makes these bulbs differ from each other is their legality within the United States. The 9003 is made as an alternative to the H4, which is still not legal in the U.S.
Sure, you can use the 9003 within and outside the country, given that you have a 9003-compatible vehicle. However, you cannot use an H4 headlight in the United States.
Presented below is a table containing essential similarities and differences between the H4 and the 9003 bulbs.
|H4 Headlight Bulb||9003 Headlight Bulb|
|Length of Base Rods||(Not specified under UN Regulation No. 37)||½ inch (Diameter)|
|Nominal Voltage (and Wattage)||12V (60-55W) and 24V (75-70W)||12.8V|
|Compatibility||H4 and 9003-Compatible Headlight Mount||9003-Compatible Headlight Mount|
|Allowed For Use?||Yes, except in the United States and other countries that specifically do not allow H4.||Yes, within the United States (in accordance with the Federal Motor Safety Standard 108).|
Frequently Asked Questions
Can I use H4 instead of 9003?
If you’re in the United States, you cannot use an H4 headlight. As prescribed under the FMVSS 108, motorists are obliged to use a 9003 headlight.
Even if you attempt to use an H4 secretly, the 9003 bulb has minor yet still noticeable specifications and features. For instance, 9003 headlights have a “DOT HB2” mark.
For your safety, please comply with the existing laws and regulations in your home country.
Are H4 and 9006 the same?
Despite having the same bulb type, the 9006 is an entirely different headlight. The 9006 has a distinct L-shape body, which is a particular feature, unlike the H4 or the 9003.
In addition, the 9006 is a single-filament headlight. It differs from the H4 and 9003’s double-filament features.
Lastly, unlike the H4 and 9003’s dual-beam capacity, the 9006 is commonly used as a low-beam light.
Is H4 brighter than 9003?
At first, it may seem that the H4 and 9003 are equal in terms of brightness. Besides, they both have the same wattage at 12V (or for the 9003, 12.8V).
But, the H4 is brighter than the 9003 in terms of their luminous flux in lumens.
This chart shows that the lumen in H4 is 20 lumens higher than in 9003 at 55W. A step up at 60W, the gap is much bigger as the H4 is 60 lumens higher than the 9003.
What vehicle uses H4 bulbs?
H4 (and, by extension, 9003 bulbs) are compatible with cars, trucks, motorcycles, buses, and trailers. Still, while you can use H4 for H4 and 9003-compatible vehicles, 9003 bulbs are only helpful for the latter.
Here is a list of vehicles that are compatible with H4 bulbs.
H4 vs. 9003 bulbs are not a matter of performance or compatibility. These bulbs are both double-filament three-prong bulbs with slight changes in their structure and use.
The most significant difference between the H4 and the 9003 is the restrictions within the United States. The H4’s widespread use in many countries across continents, the 9003 has been standardized for use in the United States.
Given these, the best way to determine which is best for your vehicle depends on your home country’s vehicle regulations. In this case, you should properly observe existing laws within your area to avoid any untoward consequences with the law.