California Window Tint Law Calculator

How California measures tint

California regulates how much visible light passes through each window — visible light transmission (VLT). What matters is the combined number: the factory glass and the film together. Two layers multiply: glass that lets in 80% of light with a 70% film gives 0.80 × 0.70 = 56% combined — below the 70% minimum for front side windows, even though "70%" film was installed.

That's why most "legal-looking" front tint fails a meter test, and why light ceramic films are the go-to for front windows in Sacramento: they cut infrared heat without darkening much.

The rules, window by window

• Windshield: non-reflective tint only on the top 4 inches. Clear UV/IR films on the rest of the windshield are a gray area — ask us before you buy.
• Front side windows: combined VLT of at least 70%. With typical factory glass, only very light films qualify.
• Rear side windows and back window: any darkness, as long as the vehicle has outside mirrors on both sides.
• Colors and reflectivity: no red, amber or blue tint; mirror-like films are restricted.
• Medical exemptions exist for certain light-sensitivity conditions with documentation — the rules and limits are specific, so read your paperwork carefully.

This calculator is an estimate for education, not legal advice. Factory glass varies by vehicle — we can meter your glass for free at the shop.