Colorado tint law
Most pages on this subject quote each other rather than the law. What follows is taken from section 42-4-227 of the Colorado Revised Statutes itself, with the wording that matters reproduced closely enough that you can check it.
The two numbers
Colorado sets the rule in terms of light transmittance, which is the share of visible light that passes through the finished combination of glass and film. Two figures carry almost all the weight.
Twenty seven percent is the floor for every window on the vehicle except the windshield. The statute prohibits operating a vehicle registered in Colorado on which any such window is treated with material that allows less than twenty seven percent light transmittance.
Seventy percent is the floor for the windshield, which the statute states directly.
That is the baseline. Everything else in the section either qualifies it or describes what happens when it is ignored.
- Windshield
- 70 percent minimum
- Front side windows
- 27 percent minimum
- Rear side windows
- 27 percent minimum, unless the exception applies
- Rear window
- 27 percent minimum, unless the exception applies
The exception behind the driver
This is the clause that decides what most people actually end up with, and it is the one most often described incorrectly.
The statute allows the windows to the rear of the driver, including the rear window, to go below twenty seven percent. It attaches one condition, and the condition is strict: the front side windows and the windshield on that vehicle must both allow at least seventy percent light transmittance.
Read that carefully, because the trade is sharper than it first appears. The front side windows do not merely have to stay legal at twenty seven percent. They have to reach seventy percent, the same figure as the windshield. In practice that usually means leaving the front side windows close to untreated.
So the choice is between two positions:
- A consistent look. Every window at twenty seven percent or above, with the front and rear broadly matching.
- Dark rear glass. The back as dark as you want, bought by keeping the windshield and both front side windows at seventy percent or above.
You cannot have dark fronts and dark rears. Deciding which of these two you want before choosing a film saves the most time of anything on this page.
Four more rules worth knowing
The windshield strip
Non transparent material may be applied to the topmost portion of the windshield. The bottom edge of that material must extend no more than four inches measured down from the top of the windshield. It may not be red or amber, and it may not distort or obstruct vision. Note that the statute states four inches. It does not refer to the AS-1 line, despite how often that claim appears elsewhere.
No mirrored finishes
The section states plainly that no material presenting a metallic or mirrored appearance may be used on any window in the vehicle. This rules out a whole category of finish regardless of how much light it transmits, and it is worth raising before anyone recommends a metallised film to you.
Factory glass is not caught
Nothing in the subsection prevents the use of a window that was treated in a manner approved by federal statute or regulation where that window was fitted as part of the vehicle at manufacture, or where such a window is replaced with equivalent glass. Deep tinted factory privacy glass is a different thing from film applied afterwards.
Two different penalties
Operating a vehicle in breach of the section is a class B traffic infraction. Installing, covering or treating a window so that it fails the requirements is a class A traffic infraction, the more serious of the two. The law weighs fitting non compliant film more heavily than driving with it.
Check the current text
This page reflects section 42-4-227 as published in the Colorado Revised Statutes 2023 printout from the Colorado General Assembly. Statutes are amended. Anyone making a decision that depends on the precise wording should read the current version rather than trusting a summary, including this one.
This is general information about a published law. It is not legal advice, and it does not account for exemptions that may apply to an individual, such as those available for documented medical conditions. A question about your specific circumstances belongs with a lawyer or with the relevant state authority.
The section also contains provisions for law enforcement vehicles and for windshield wiper equipment that are outside the scope of this guide.
Work out what this means for your car
The limits set the ceiling. Choosing the material underneath it is the other half of the decision.