Free Tool
VLT Calculator
Visible Light Transmission — the percent of light that passes through a window after tint.
A 35% film on 75% factory glass gives a net 26.25% VLT — not 35%. See the real number, then compare it to your state's published minimum.
What is VLT?
VLT stands for Visible Light Transmission. It's a single percentage: how much of the light hitting your window makes it to the inside of the car. A 5% VLT window blocks 95% of light and looks nearly black. A 70% VLT window blocks 30% of light and looks almost clear.
Two things matter: the film's VLT (printed on the box) and your factory glass's VLT (most cars are 70–80%; SUV rear privacy glass can be 15–25%). They multiply. The number a police tint meter reads is the combined result, not the film percentage.
≥ 32% VLT required on front sides
Net VLT through tinted window
26.2%
75% factory × 35% film
Information only — not legal advice. State VLT data summarizes 2025 published DMV guidance. Laws change, medical exemptions exist, and enforcement varies. Verify with your state DMV before installing.
How the math works
Net VLT = factory glass VLT × film VLT, both expressed as decimals. A police tint meter reads this combined number — not the film percentage on the box.
Why factory glass already cuts light
Most modern automotive glass ships at 70–80% VLT. Privacy glass on rear windows of SUVs and trucks can be as low as 15–25% VLT before any film is added. Check the bottom corner of your rear glass for the AS-2 or AS-3 marking and a VLT spec, or assume 75% for clear front-side glass.
What happens if you're below your state's minimum
Common penalties are a fix-it ticket plus a fine ranging from $50 to $250 for a first offense. Some states require film removal and re-inspection. Medical exemptions are available in most states with documentation from a licensed physician — typically dropping the front-side minimum by 15–20 percentage points.
FAQ
What does VLT mean?
VLT stands for Visible Light Transmission. It's the percentage of visible light that passes through a window. A 35% VLT film blocks 65% of visible light.
Why is my net VLT lower than the film percentage?
Factory automotive glass already filters some light — most cars ship with 70–80% VLT glass. Film percentages multiply with factory VLT, so 35% film on 75% glass yields a net 26.25% VLT, not 35%.
How is the legal VLT measured during inspection?
Police use a tint meter applied to the rolled-up window. The meter reads the net VLT — film plus factory glass combined — which is the number this calculator gives you.
Does this apply to ceramic, carbon, and dyed films equally?
Yes. VLT math is the same across film types. Ceramic films cost more because they reject infrared heat better at the same VLT, not because they let through different amounts of visible light.
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