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W21W (7440, T20, WY21W) Bulbs

By 02.06.2021lamps

Does your car headlight use a W21W bulb? Then this guide will help you make the right choice among the many bulbs that are on the market.

If you need help choosing a bulb for your car, read our guide to choosing a car lamp, or use the lamp selection for each car model on our website.

W21W Bulbs Guide

Types of bulbs
Bulbs Review
Buying Guide

Best W21W bulb

What is a W21W bulb?

W21W lamps are quite versatile, such lamps are installed in the license plate lights, rear parking lights, interior lights, trunk lights, front parking lights.

W21W lamps are currently one of the most popular bulbs on the market due to their design and good sealing.

Full High Beam Headlight Flasher

Variety of W21W car bulbs

W21W bulbs are most commonly installed in dipped beams and fog lights. Depending on the light source, W21W dipped-beam bulbs are available in different versions:

  • Halogen bulbs
  • LED bulbs

Best W21W Bulb Editor’s Choice

SYLVANIA ZEVO 7440/T20 LED Bulb

SYLVANIA ZEVO 7440/T20 LED Bulb

Product information:

  • 6000 Kelvin
  • Lifetime Warranty
  • Shock and vibration-proof for durability
  • 360° illumination Festoons

★★★★★ 4,9 Rating

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Types of W21W bulbs

  1. Halogen Bulbs
  2. LED Bulbs

W21W Halogen Bulbs

The halogen W21W bulb is arranged as follows: the filament is located in a bulb, the material of which is carbide or quartz glass.

Halogen W21W bulbs are easy to install, inexpensive, and good performance. Along with these advantages, halogen lamps have a disadvantage. During operation, they heat up to a high temperature.

Halogen W21W bulbs have a good price to quality ratio, which is the reason for their frequent use. Currently, among the manufacturers of W21W bulbs, there are several leaders in terms of brightness. These brands are OSRAM, Philips, SYLVANIA, the brightness of these lamps is 150% higher than the standard lamp.

Halogen W21W bulbs are fully approved for on-road use in all states and are warranted by the manufacturer. We have chosen incandescent bulbs with 150% more light, these W21W halogen bulbs are the brightest on the market.

These bulbs are easy to install because you replace halogen with halogen, and you have no problem installing them. The disadvantage of W21W halogen bulbs is their lifespan.

The brighter the light, the shorter the life of the W21W bulb. This is because there is a filament inside the W21W bulb, which burns out quickly. If you want a long life, use LED bulbs.

Best W21W Halogen Bulb

Philips 7440 CrystalVision Ultra Bulb

Product information:

  • Type of Bulb Halogen
  • Bright white light

★★★★★ 4,8 Rating

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SYLVANIA 7440 SilverStar High Bulb

Product information:

  • Type of Bulb Halogen
  • Base W3x16d
  • Voltage 12V, Wattage 24.98W

★★★★★ 4,8 Rating

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Best W21W LED Bulbs

LED W21W bulbs are usually brighter than halogen bulbs. They last much longer, use less energy, and are easy to install.

The W21W LED lights are often the perfect choice for those looking for clean, bright, white light. Today, they are considered one of the best. This fact is due to their following advantages:

  • Low power consumption
  • Large operating term
  • Resistance to mechanical vibrations

The lighting device based on diodes is suitable for both low and high beams. In addition to the positives, LED W21W bulbs have a disadvantage – the high cost. LED-lamps from halogen lamps differ in that the latter are spotlight sources. LED bulbs consist of a cylinder on which LEDs are installed. The most popular W21W LED bulb manufacturers: OSRAM, Philips, BEAMTECH, HIKARI, Fahren, Cougar Motor, NINEO, Aukee, AUTO ONE, CAR ROVER, and others.

Best W21W LED Headlight Bulbs

OSRAM LEDriving W21W

Product information:

  • LED Bulbs
  • Voltage 12 Volts

★★★★★ 4,9 Rating

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Philips 7440 Ultinon LED Bulb

Product information:

  • 6000K
  • Up to 8 year lifetime

★★★★★ 4,9 Rating

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AUXITO T20/7441 LED Bulbs

Product information:

  • 6000 K
  • 2600 LM
  • 360° high luminous efficiency
  • 30 Volts

★★★★★ 4,9 Rating

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AUXLIGHT W21W LED Bulbs

Product information:

  • +320% BRIGHTER
  • Voltage 24 Volts
  • Wattage 4 watts

★★★★★ 4,8 Rating

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Yorkim 7440 Led Bulb

Product information:

  • 400% brighter
  • 360° viewing angle
  • Longer life span up to 50,000 hrs

★★★★★ 4,8 Rating

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W21W Bulbs Review

A review of W21W bulbs can boil down to a few parameters

It is the type of W21W bulb: halogen bulbs, LED bulbs, or xenon lamps. The next factors are the brightness of the bulbs and the color of the lamps.

Lamps with a W21W base are used for cars with high mileage, which means that the optics will not be in the best condition: faded reflector, cloudy diffuser. In this case, the most interesting option for purchase is lamps with increased luminous efficacy. Careful when buying bulbs with increased brightness and need to be to their light distribution – if they will start to blow on the oncoming lane, the drivers there will be much more noticeable.

The normal practice among well-known manufacturers to indicate on the packaging that the lamps are designed exclusively for off-road use only (for off-road use): For example, such lamps can be put in the headlight-seeker or headlamp chandelier raid car, but on the road, they really have nothing to do.

As for the color temperature, of course, you can choose any, except that white, going into a bright blue. However, the saturated yellow glow is still better left for the fog lights with transparent diffusers, the main light to make whiter: each color has its own advantages, and here in this combination they are best revealed.

W21W Lamp socket

Make sure you buy the right type of bulb for your car. W21W bulbs are bulbs for a car headlight or for fog light. You can determine what type of bulb you need for your car by checking this information in your owner’s manual. You can also find out what type of bulb you need by using the bulb selection by make and model of your car using our website. On the car bulb finder page, you will find information on what type of bulbs you need to use.

W21W Bulbs Buying Guide

Once you’ve determined that W21W bulbs are what you need, you can start searching for the brightest W21W bulbs. When choosing an W21W bulb, you need to consider the following factors:

  • Light distribution on the road
  • Power consumption
  • Luminous flux
  • Compliance with light distribution with established standards

Power of W21W bulbs diode

The power of the LED depends on the brightness of the light it emits, and the higher the quality of the diode, the higher its efficiency will be. We do not recommend that you choose the most powerful and brightest models for your vehicle.

Dependence of power from the cooling system W21W bulbs

An LED generates a lot of heat when it emits light, and the higher the wattage of the lamp, the more heat the lamp produces. Poor cooling or poor quality results in the LED not being able to operate at full power.

The noisiness of the W21W bulbs cooler

If your choice fell on a powerful W21W lamp with active cooling, then note that the cooler’s poor quality lamps are not only more likely to fail but also create a certain noise and vibration, which can be heard in the cabin. Constant monotonous barely audible hum sooner or later will drive even the most sedate driver crazy.

The brightness of W21W bulbs

It is customary to measure the brightness of a lamp in lumens, this value indicates how much light you get from the lamp. Lumens indicate the amount of light distributed by any light source. The more lumens, the brighter the light from the lamp. At the same time, fewer lumens give less light.

Bulb Light

Color temperature W21W bulbs

The most popular W21W LED bulbs have a color temperature of 5000-6000K, such a bulb is suitable for most cars. If you prefer the yellow color of the headlights, it is better to choose a W21W lamp with a temperature of 4000K, such a lamp will be less bright, but more natural for the eyes. Brighter light sources with a temperature of 5000-6000K provide better visibility in rainy weather when the lamp is properly focused than similar light sources with a yellow spectrum. Do not raise the color temperature of the lamp too much and choose W21W bulbs with 7000-8000 K, regardless of optics and focus, they will not provide the same quality illumination. Modern W21W LED lamps are capable of producing light with different color temperatures:

  1. Warm white (up to 3500 K)
  2. Neutral white (4200 to 5000 K)
  3. Cold white (temperature 6000 to 10000 K)

Temperature Kelvin

How do I install a W21W bulb?

To facilitate installation in cramped conditions, the ring of the base on all the bulbs is made removable. First, the ring of the base is installed, clamped by a locking device, then the W21W diode bulb itself is placed. Sometimes there are problems when installing the light bulb in the headlight, the headlight cover does not close when the cooling system is placed.

Always remember that the choice of automobile lamps W21W for dipped beam – a responsible thing because they determine the safety of the road.

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