VLT is the number every tint conversation runs on, and half the people quoting it don't actually know what it measures. Getting it wrong is how you tint a car illegally.

VLT stands for Visible Light Transmission. It's the percentage of visible light that passes through the film and glass. Lower number, darker tint. A 5 percent film (limo) lets almost no light through. A 70 percent film is nearly clear. So when a state law says "35 percent minimum on front windows," it means the film plus glass has to let at least 35 percent of light through. Go darker than that and it's a ticket.

Installers forget one catch: the glass already has its own VLT before any film goes on. Factory glass is often around 70 to 80 percent. Layer a 35 percent film over 78 percent glass and the net reading on a meter comes out lower than 35. If a customer needs to pass an inspection, measure the net, not the film box.

VLT does not tell you heat. A dark film can block little heat, and a light film can block a lot. That's the ceramic sales pitch in one line.

TSER, Total Solar Energy Rejected, is the honest heat number. It's the percentage of total solar energy (visible light, infrared, and UV combined) that the film rejects. Higher is better. This is the figure to compare films by, because it covers the whole spectrum, not one slice.

IR rejection, infrared rejection, is the percentage of infrared, the heat you feel on your skin, that the film blocks. It sounds impressive and marketers love quoting a big IR number over a narrow band. Useful, but TSER is the fuller picture. Don't let a 90 percent IR claim distract from a mediocre TSER.

Spec the job this way. Pick VLT for the legal shade and the look. Then check TSER for real heat performance. Use IR rejection as supporting detail, not the headline. Quote all three and you sound like someone who knows the product, because you do.

Want a spec sheet with VLT, TSER, and IR for every shade, plus a free tint sample? See highcool.com/pages/wholesale-free-sample.

FAQ

What does VLT mean in window tint?
VLT is Visible Light Transmission, the percentage of visible light that passes through the film and glass. Lower VLT means darker tint. Tint laws are written as a minimum VLT, for example 35 percent on front side windows.

Is VLT the same as heat rejection?
No. VLT only measures visible light and darkness, not heat. For heat, look at TSER (total solar energy rejected) and IR rejection. A light film can still block a lot of heat, which is the whole point of ceramic tint.

What's the difference between TSER and IR rejection?
TSER is the percentage of total solar energy rejected across visible, infrared, and UV combined, so it's the fuller heat number. IR rejection covers only the infrared band. Compare films by TSER and treat IR as supporting detail.

Shops stocking film for these jobs can see current shades and VLT options in our window tint film collection.