Sunglasses categories: a guide to know more about filters and lenses

If you’re among those who are wonder about what the different categories of sunglasses are, or what the filter is made of on your lenses, or if you just want to know a little more about how sunglasses protect your eyesight, then you need to read this article.

What you’ll learn:

  • What the categories of sunglasses are.
  • What the categories are of sun filters.
  • What type of sunglasses filters are right for each activity.

So let’s get started!

What are the categories of sunglasses out there?

One of the most frequent questions that come to us is in regards to the category or tone of our lenses.  Before we answer, we want to first tell you about what these categories and filters mean.

It’s an ISO standard that’s called ISO 8980-3. All right, well, you might have stayed the way you were, right? Don’t worry, we’ll explain what an ISO standard is.

The acronym ISO is derived from the International Organization for Standardization, so an ISO standard is a standardization of products and services that are provided by this organization.

That means that each category or filter of sunglasses has been assigned a certain value. And this is done in order to guide consumers about what they are purchasing.

Because the sun is not equally intense at all times, during all seasons of the year or at all latitudes around the world, it may be advisable to wear a different category of sunglasses for each situation.

Before we go any further though, you need to know this:

The category of sunglasses is not the same as their UV absorption filter. When we talk about the category or filter of sunglasses, we are referring to the level of darkness provided by the sunglasses, also known as the level of light absorption. This is called Visible Light Transmission, VLT.

It’s possible to find very dark glasses that absorb a lot of sunlight but don’t have a good UV filter: this type of sunglasses are commonly found in your everyday supermarkets.

The categories of sunglasses are classified by their absorption of sunlight (or by the sunlight they transmit).

You need to know that the percentages shown here are indicative, a variation of 2-3% above or below is acceptable to place a pair of sunglasses in one category or the other.

Now that this has been made clear, let’s move on to the next point.


Take a look at this chart:

sunglasses categories

And now let´s explain this,

Category 0:

When it comes to light transmission, these sunglasses transmit between 80 and 100% of the light. On the other hand, if we’re talking about absorption then these lenses would absorb between 0 and 20% of sunlight. As you can see, these values are inverted.

The sunglasses with these sun filters would be ideal for very cloudy days, for hours close to sunrise or sunset, for interiors, and they are suitable for driving or any other type of daily activity.

Let’s go to the next category.

Category 1:

The light transmission for this category is around 42-80 %, so the absorption rate is between 20 and 58%.

These are glasses that you could wear on partially cloudy days. They are suitable for driving, except at night, and it’s recommended to use them in conditions where there is no prolonged exposure to the sun. These are not recommended for outdoor athletic activities.


Category 2:

They have a light transmission rate of 18 and 42%. In other words, they have an absorption of between 58 and 82%.

These are lenses that are suitable for driving and recommended for use on cloudy or clear days. They can also be used in sports where there is no excessive sun exposure involved.

Now we’re moving on to the most famous category…

Category 3:

Cat 3 sunglasses are the top-selling item in the industry, and this is due to its high degree of sunlight absorption, consisting of 82-90%. If we are talking about transmission, then you know that the opposite figure must be applied: 8-18%.

This is a category that is suitable for daytime driving and offers comfortable protection against the sun’s rays. When I say comfortable, what I mean is that we feel that that the sunglasses fulfils one of its tasks, which is to prevent sunlight from bothering or blinding us.

These Category 3 sunglasses are recommended for all types of outdoor activities, such as spending a sunny day out in the country or on the beach. This is also perfect for all types of sports, with the exception of the ones that we will mention below.

All of our lenses are Category 3 sunglasses


  • Photochromics that range from Category 0 to 3.
  • Clear and yellow lenses are Category 0.

And now we are going to move on to the last category.

Category 4:

This is a type of sunglasses that incorporates lenses with a light absorption capacity of over 91%, which can reach up to 98%.

These are very specific lenses used for situations involving extreme sunlight, such as sports, sailing, or activities in the high mountains (skiing, snowboarding, etc).  Keep in mind that with snow or water sunlight reflects much more as opposed to asphalt or grass. That’s why these types of activities require extra protection against sunlight exposure.

olympic sunglasses

However, these lenses are not suitable for driving, and the police may even fine you if you wear them while you’re behind the wheel.

We’re convinced that this information will be useful towards your next purchase of sunglasses. Keep in mind that these categories are rather subjective.  

While you may feel comfortable with a Category 1 pair of shades on sunnier days, another person may not think so. Each eye and visual system is different, and you should be the one to test those sensations, based on what’s mentioned in this article.  (Exception: Category 4 is only for extreme sunlight exposure)

And this is it. We hope you liked this article and share it on your social networks

See you soon!

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