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Low Beam vs High Beam - Understanding Headlight Functions


When shopping for new headlight or fog light bulbs, whether replacing your stock halogens or looking to upgrade to a brighter alternative such as LED headlights or Xenon HIDs, you will come across different bulbs for different beams.

In order to purchase the right product, it's important to understand the different beams, when they are used and their purpose. In short, the low beam is the primary source of light and most frequently used lighting function while the high beam is a secondary source of light used rarely in very dark settings such as on dark roads, the country, etc.

After reading this guide, you'll understand the differences between low beams and high beams. We'll also explain when you should use your low beams and high beams and conclude with some questions we frequently receive from our customers on this topic.

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Low Beam vs High Beam Headlight Function

The difference between low and high beams is that low beams are used for normal nighttime driving while high beams are used in rural areas or small roads with very little or no light at all.

Low beams are angled towards the road and should be always kept on in low light settings while high beams are angled upwards for extra light and should only be used for very short periods of time as to not blind other drivers.

All cars have a low and high beam function and most drivers should already know the difference between the two since it's a prerequisite before getting your license.

Low Beam vs High Beam Headlight Function

Low Beam vs High Beam Comparison

  High Beam Low Beam
Beam Angle Straight/Upwards Towards the ground/road
Focus Long-range Short-range
Light Coverage ~100 meters ~40 meters
Best For No light environments (rural areas, small roads, etc.) Normal Nighttime driving / low light environments
Activation Period Short period / as long as no other cars are within 150 meters Must always stay on when in low or no light environment
Blind other drivers Yes No
Activation Manual Automatic or Manual
Legal Yes Yes
Halogen Yes Yes
LED Yes Yes
HID/Xenon Yes Yes

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What are low beams?

Low beams are the 'normal' lights your car headlights emit and are used when driving at night or in a dim or dark setting such an indoor parking lot. Low beams have a short-range focus and are sometimes referred to as 'dipped beam'.

Low beams are the most important and most frequently beam used in a car. The light beam is angled towards the ground in order to illuminate the road and to avoid blinding other drivers. They are a way for other drivers to see you.

Traditionally, drivers would have to manually turn on their low beams but newer cars do so automatically by detecting low light environments such as during the night or when entering a dim parking lot.

What are high beams?

The high beam headlight lighting function is normally activated in environments with little to no light such as the country or small roads with no street lights. High beams are sometimes referred to as 'brights' or 'full beams'.

The light beam for high beams is angled upwards in order to illuminate a surface area above and beyond the light of the low beams. High beams have a long-range focus.

Unlike low beams, high beams will never turn on automatically. They must be manually turned on by the driver when needed. In fact, high beams should only be used for short periods of time when extra light is really needed.

Driving with your high beams can blind oncoming traffic, which can be very dangerous. Keeping them on for an extended period of time is illegal.

Dual-Beam Headlight Systems

All cars and trucks come with a low beam and a high beam function, however, some cars require two separate bulbs for each beam (single beam systems) while others require only one bulb (dual beam systems) for both.

Drivers that have cars with dual-beam systems will only need to buy one set of bulbs to replace (or upgrade) both low and high beams. Dual-beam bulbs are typically slightly more expensive than single beam bulbs and draw more power.

To learn more on these two types of headlight bulb systems check out our guide on Single Beam vs. Dual Beam headlight bulbs.

Frequently Asked Question (FAQ)

How do I activate my high beams?

High beams need to be manually activated, unlike low beams for most new cars. High beams can be activated using the blinker lever. Some cars require you to push while other require you to pull the lever towards you.

Do the low and high beams use the same bulb size in single beam systems?

This entirely depends on your car. Some cars happen to use the same bulb size for each of the high and low beams in a single beam system while others use completely different bulb sizes. In the event that they are the same, you will need to sets of bulbs, one set for your lows and another for your high beams.

Are high beams brighter than low beams?

Yes. High beams will produce a greater amount of light but simply due to the angle and position within the headlight.

Are high beams legal?

Yes. Using your high beams is legal but should not be using continuously as they blind other drivers. High beam usage should be restricted to very dark environments with little to no oncoming traffic.

What is the difference between high beams and brights?

None. Brights is just another term used for high beams and originates from the extra brightness produced by the high beam.

Should I use high beams in rain, snow or fog?

Not recommended. Using your high beams in such weather conditions would cause the light to reflect back at you. In very low light settings, high beams can be used temporarily.

Do cars have automatic high beams?

Yes, in cetain newer cars. Automatic high beams work using a sensor and a forward-facing camera (normally mounted on the rearview mirror).

The sensor detects low light levels while the camera detects oncoming traffic in order to dim the lights and prevent blinding other drivers.

Are fog lights the same as low beams?

No. Fog lights are a separate beam, only come on certain cars and are not required by law. Fog lights are typically found in the front bumper of a car or truck in their own separate assembly.

Low beams and high beams are found in your car's headlight assembly which typically sits on top of your front bumper.

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