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Understanding Tint Percentages

How Are Window Tint Percentages Calculated?

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Car window tinting films are measured in visible light transmission levels (also known as VLT), and these levels are represented as a percentage of the visible light transmitted through the windows. So, when you see a window film being referred to as a percentage, this is the VLT. “Let’s do 35% on the back windows,” means 35% of the visible light will pass through the window film.

In the simplest terms, the lower the percentage, the darker the window film will be. A 5% VLT film is very dark as it only lets though 5% of visible light and a 70% film is very light as it lets through 70%. There is, however, one little complication, and that is that windows as installed by the factory do not allow 100% of light to pass through. Most auto makers very slightly tint their glass, usually with a VLT of about 80%.

So how do you calculate the true VLT of your windows?

To calculate the actual VLT of the glass with film applied to it, you need to multiply the VLT of the window tint applied by the VLT of the glass. For example, applying a 5% film to glass with an 80% tint to it, you would multiply 5% x 80% = (0.05×0.80)x100 = 4%. So the glass and window tint would have a combined VLT of 4%.

Is there a way to test my windows for their current VLT %?

As a matter of fact there is! Most installers will be able to tell you with one look and be correct within about 5%, that is because we do this all day, everyday, and you get to know your product pretty quickly. Law enforcement officials and many professionals might use a device to get a VLT reading that is extremely precise. Here is an example of one. You clip it on your window and it uses a laser to test the permeability of the window film. Its a cool piece of gear for petrol-heads, pros, and anyone super keen on the window tinting game.

This Post Has 13 Comments
  1. Hi,
    Is there a website you know of where I can find the original tint level of a window? I know newer vehicles have tinted factory, but what is newer? I have a 2003 Grand Marquis and am looking at getting the side windows to 30% if they are not there already. Should I just hunt down someone with that piece of equipment and ask?

    Cheers for the informative article.

    1. Hi there, I believe you would need a Tint-Chek tint meter to learn the true visible light transmittance of your windows. If you want to send us a note though our contact form we may be able to help. We have seen enough windows to know 🙂

  2. I know on my 2014 GMC Sierra, the tint percentage is in the lower right corner of the glass. 70% is the standard factory tint for the two front side windows. I am adding 35% tint to them, which will give them a combined 25% VLT, legal limit of tint in Texas.

  3. I have a black 2016 Chevy Cruz with black interior and I wanted to know if 35% on the front windows would allow for someone to clearly see me, inside my vehicle, at night.

    1. 35% is a pretty good mid point, we often recommend it. Just send us a message through the contact form if you would like more specific info.

  4. Hi,
    Enjoyed the article. I’m looking to tint the windows on a Tesla Model 3. Do you know the factory glass TLV? What tint %TLV would you recommend for rear window? Side windows? Would you also recommend front window or not?


    1. Hi there, I am going to send you an email with some info. All questions about services and quotes should go through our contact page in the future.

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