What are the 5 sunglasses categories?

Sunglasses lenses are categorised by darkness of tint. There are five categories in total which absorb measurably different amounts of light through the lens. These tints range from very light (category 0) to extremely dark (category 4.)


So, are darker lenses better then?

No. Lens darkness has nothing to do with UV protection. The category of your lenses simple measures how much visible light they absorb. The darker the tint, the more light they absorb which can make it more comfortable for you to see. UV is invisible light and must be blocked, regardless of the sun lens category.

 In this article, you can learn about the 5 sunglasses categories and how they affect the way you see when looking through each type of lens.


5 sunglasses lenses with different levels of tint darkness

What are the 5 lens categories?

The five lens categories are defined by their visible light absorption percentage. Abbreviated as ABS%, the five categories range from 0,1,2,3, and 4 with increasing levels of absorption as seen in the table below.








0% - 10%

10% - 20%

20% - 43%

43% - 80%

80% – 92%


Very light




Very dark

Sun use





Very strong

Driving suitability

Day & night

Day only

Day only

Day only



Optical lenses being darkened in colour tint baths

How are lenses darkened?

Sun lenses are made by darkening a prescription or non-prescription lens with a tint colour such as grey, green or brown.

Depending on the darkness required, their visible light absorption percentage (ABS%) is controlled by the duration of which they're immersed in the tint. This occurs in a heated liquid bath of dye which penetrates the uncut lens (seen below).

ABS% denotes the amount of light absorbed by a sun lens which can be anything between 1% or 100%. It’s this percentage that informs the five sunglasses categories.


What category of sun lenses is best?

Depending on your application, most recreational sunglasses use category 2 or 3 lenses for tasks like driving, walking and sport.

Category 1 lenses are very lightly tinted, with little to no darkening effect. This is usually insufficient for bright sunny days are are more often used for fashion purposes or light sensitive eye conditions.

Category 4 lenses are considered specialist for high-exposure scenarios like mountaineering and are in fact illegal for driving in the UK.

For more details, check out the following descriptions and applications of the 5 lens categories in the list below.


What are category 0 sunglasses?

Category 0 lenses have little to no tint which barely reduces the darkness of the lens. With as little as 5% of the light being absorbed, category 0 lenses are vaguely tinted and are used for prescription spectacles.


What are category 1 sunglasses?

Category 1 lenses  have a more obvious colouration from tinting, but would still be far too light for use as everyday sunglasses. Category 1 lenses are basically a coloured spectacle lens which offer mild relief on bright days. A popular choice for people who live in very sunny locations or have sensitive eyes.


What are category 2 sunglasses?

Category 2 lenses  are the halfway point between a very dark spectacle lens and a light sunglasses lens. Their colouration is prominent and absorbs less than half of sunlight through the lens. Category 2 lenses could be used as sunglasses on moderately bright or overcast days.


What are category 3 sunglasses?

Category 3 lenses absorb around two thirds of visible light which makes them suitable as everyday recreational sunglasses for activities such as sport, driving or a blue-sky day on the beach. Banton Frameworks sunglasses are category 3.


What are category 4 sunglasses?

These are the darkest sun lenses. Because they absorb so much visible light, they’re illegal to wear for driving. Generally, these lenses are only suitable for extreme exposure scenarios such as high-altitude mountaineering. Not your everyday sunglasses lens.


What are category 5 sunglasses?

Category 5 lenses are considered the same as category 4 lenses if you start from 1 instead of 0. These lenses absorb up to 92% of visible light and are extremely dark to look through. They are designed for high exposure excursions, usually with side shields for the prevention of snow blindness for mountaineers.



Strong sunlight bursting through clouds on a sunny day

What does uv400 mean on sunglasses?

UV400 or UV40 sunglasses have lenses which block 99-100% of UVA and UVB (ultraviolet) sun light. This means they properly protect your eyes from the most damaging frequencies up to 400 nanometres, hence the name.

You must remember that regardless of sunglasses categories, protection against ultraviolet light is the single most crucial factor of any pair of sunglasses.

Truth be told, the darkness of a lens has nothing to do with UV protection. Tint only reduces the amount of visible light which can pass through a lens and doesn't block any UV.

Ironically (and dangerously) a very dark lens without UV filtration would make your pupils dilate to let more visible and UV light-in. This would seriously damage your eyes and could lead to significant or permanent damage such as cataracts, photokeratitis, macular degeneration or even blindness.

Always check that your sunglasses are rated with full UV protection.

At Banton Frameworks, all our sunglasses are 100% UV protective in compliance with European standards.


Illustrating how ultraviolet light is blocked by UV400 sunglasses

Visible light can pass through a UV400 sun lens | UVA & UVB cannot pass through | UVC is absorbed by the atmosphere


Is 100% UV protection same as polarised?

UV protection is not the same as polarised lenses. Protection from ultraviolet light is mandatory whereas polarisation is an optional upgrade to help reduce glare from reflected and overhead sunlight.

Polarised lenses must always be UV protective, but they also contain an additional filter called a polariser. This filter is a chemical film which is built into the layers of the lens construction.

Upon the filter are microscopic rows of molecules which are vertically aligned in relation to your eyes. This creates a filter which blocks-out most horizontally orientated light.

But what is horizontal light?

Horizontal light occurs when it’s reflected off molecules in the air or when it bounces off large shiny surfaces such as water, snow, buildings or cars. These flat surfaces re-orientate and condense the light into what is called glare.

Glare is painful to look towards and boy does it interfere with your vision. Especially when you’re trying to drive your car, play sport or just see clearly.

Because of their in-built filter, polarised sunglasses can block most of this distracting glare from entering your lenses; making them more consistent and smoother than regular sun lenses.

This is why they're such a popular choice for sunglasses for driving or if you play outdoor sports.


Illustration showing how polarised sunglasses reduce horizontally polarised light



  • Lenses are categorised into 5 types, ranging from light to dark.
  • Tint darkness is measured as a percentage called visible light absorption or ABS% for short.
  • Sunglasses must be 99-100% protective against ultraviolet light and state or be accompanied with the UV40 or UV400 rating in compliance with European law.
  • Lens darkness has no relevance towards UV protection as is merely a personal preference based on how you use your sunglasses.
  • Category 4 lenses are illegal for use whilst driving and are best avoided unless you require them for extreme exposure scenarios.
  • Polarised lenses are a secondary option and have no effect on UV protection. They are simply used to reduce reflected glare.


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