Window Tint Specs Explained: VLT, UV, IR and TSER — What the Numbers Actually Mean

Every tint spec sheet throws the same alphabet at you — VLT, UV, IR, TSER — and most shops are happy to let the confusion sell whatever's on the shelf. Here's what each number actually measures, which one predicts a cooler car, and the honest difference between a $229 film and a $429 one.

VLT — How Dark It Looks

Visible Light Transmission is the percentage of visible light that makes it through the glass and film together. A 5% film is limo-dark; 70% looks nearly clear. Two things to burn in:

• VLT is the legal number. New York checks front side windows with a meter at every annual inspection — they must read 70% or better. (Full breakdown in our NY tint law guide.)
• VLT is not a heat number. Darkness controls light, glare, and privacy. It tells you almost nothing about how hot your cabin gets — that's the job of the specs below.

UV Rejection — The Health Number

Ultraviolet is what fades interiors, cracks dashboards, and damages skin — dermatologists see more sun damage on drivers' left sides for a reason. Here's the honest part: almost every professional film blocks up to 99% of UV, from entry dyed film to flagship ceramic. UV inhibitors live in the polyester and adhesive, not in the fancy layers. So when a shop leads with "99% UV protection!" as if it's premium — that's table stakes, not a selling point.

IR Rejection — The Heat You Feel

Roughly half of the sun's energy arrives as infrared — the radiant warmth you feel on your arm at a red light. This is where film construction starts to matter: dyed film absorbs some IR into the glass (and re-radiates it at you), while ceramic particles physically block it. One caveat: IR numbers are the easiest spec to inflate, because a brand can quote a narrow slice of the IR band and claim "96% IR rejection." Useful, but read it next to TSER.

TSER — The Only Number That Can't Hide

Total Solar Energy Rejected is the percentage of the sun's entire energy — infrared, visible, and UV combined — that the film keeps out of your cabin. It's the closest thing tint has to a horsepower figure:

Film type	Typical TSER	What that means in July traffic
Dyed film	15–30%	Looks the part; the cabin still cooks
Ceramic film	45–65%+	Noticeably cooler cabin, AC works less

Compare films at the same VLT and let TSER break the tie. A 70% VLT ceramic film — nearly clear, fully legal on NY front windows — can reject more total heat than a dark dyed film. Read that again: the legal-clear ceramic can out-cool the illegal-dark dye.

So What's Dyed Film Actually For?

We install dyed film and we're straight about what it is: a style and privacy film. You get the look, the glare cut, and the same ~99% UV protection as everything else on the wall — at the friendliest price. What you don't get is meaningful heat rejection, and over the years dye can fade toward purple where ceramic won't. If your priorities are looks and budget, dye is a fair buy. If you park outside, commute in summer, or care about the AC keeping up on the Cross Bronx — the heat problem is solved by ceramic, not by going darker.

How to Read Any Spec Sheet in 20 Seconds

• VLT → pick your look, then check it's legal where it's going (NY: 70%+ fronts, always).
• UV → should say ~99%. If it doesn't, walk away.
• IR → nice to see high, but ask over what band it's measured.
• TSER → the number to compare shops and films on. Same VLT, higher TSER wins.

The WRP Wall

Every film we install — United Dye, United Ceramic, and STEK ceramic — is metered on your glass so it passes NY inspection, and we'll show you the spec sheet for each before you pick. No mystery rolls, no inflated IR claims: pick the look with VLT, pick the comfort with TSER, and we'll tell you plainly when the cheaper film is the right call for how you drive.