Each state, Canadian province and Puerto Rico has tint laws governing the darkness, reflectivity and colors allowed on vehicles. Window tinting laws vary from state to state and can change quickly. Before installing any window film on any vehicle, consult your local law enforcement for laws regarding the correct use and legal installation of any aftermarket window film that will be applied to your vehicle. Below are links to tint laws as published by the International Window Film Association.
Window Tint Laws
How dark can my car's tint be? Darkness of tint is measured by Visible Light Transmission percentage (VLT%). In Florida, this percentage refers to percentage of visible light allowed in through the combination of film and the window.
Windshield: Non-reflective tint is allowed along the top of the windshield above the manufacturer's AS-1 line.
Front Side Windows: Must allow more than 28% of light in.
Back Side Windows: Must allow more than 15% of light in.
Rear Window: Must allow more than 15% of light in.