Legal tint in Florida on each window, and what happens to it when the glass gets replaced
Legal tint in Florida depends on the window, because the state sets a different limit for almost every piece of glass on your car. The short version: your windshield can only carry a nonreflective strip above the AS-1 line, your front side windows must let at least 28 percent of light through, and your back side and rear windows must let at least 15 percent through — 6 percent if the vehicle is classified as a multipurpose passenger vehicle, which covers most SUVs, vans and many crossovers. The rules live in Fla. Stat. §§ 316.2951–316.2957. Everything below is the detail that decides whether your car passes or gets a ticket, plus the part almost nobody thinks about until it happens: what a broken window does to tint you already paid for.
VLT is the number Florida tint law measures
Tint is measured in Visible Light Transmission — the percentage of light that makes it through the glass and the film together. Lower number, darker window. A "35 percent tint" film does not produce a 35 percent window, because the glass underneath already blocks light on its own. Most factory auto glass runs somewhere in the low-to-mid 70s before any film touches it, so a 35 percent film on a 75 percent window lands closer to 26 percent measured. That is the arithmetic that catches people out on front doors, where Florida's floor is 28 percent. An officer's meter reads the finished window, not the box the film came in.
Florida windshield tint law: the AS-1 line is the whole rule
Under § 316.2952 you may apply nonreflective tint to the windshield only above the AS-1 line — the small marking etched into the glass a few inches down from the top edge on the driver and passenger sides. That is the visor band, and it is the only tint the statute permits on a windshield. Full-windshield film, including the clear ceramic heat-rejection films that have become popular in Tampa, St. Petersburg and Orlando, is not authorized by the Florida statute regardless of how much light it lets through.
There is a practical reason beyond the law. Modern windshields are structural and increasingly optical. The forward-facing camera for lane keeping and automatic emergency braking looks through a specific window in the glass, and so does a head-up display projector. Film, adhesive residue or a mismatched shade in that zone can degrade what the camera sees, which is one of the reasons a windshield replacement is followed by ADAS recalibration on any vehicle equipped with camera-based driver assistance.

