Legal window tint shades vary by state, but every state uses the same measuring stick: Visible Light Transmission, or VLT, the percentage of outside light that passes through the glass and any applied film together. Federal law sets a 70% VLT floor for the windshield and the front side windows, and states take over from there, almost always allowing darker tint on the rear glass than on windows near the driver. A higher VLT percentage means a lighter window; a lower percentage means darker tint.
What VLT Percentages Actually Look Like
VLT is the only number that matters for tint legality. A window at 70% VLT lets in most of the daylight and looks nearly clear. At 35%, it blocks about two-thirds of incoming light and takes on a noticeable smoke appearance. At 5% VLT, almost no light gets through, which is why that level is commonly called limo tint.
The common tint levels break down like this in practice:
- 70% VLT. Nearly clear. The federal minimum for windshields and front side windows. The interior is easy to see from outside.
- 50% VLT. A mild tint that cuts glare and heat without dramatically changing how the window looks. Legal for front side windows in many states.
- 35% VLT. A popular middle ground. Noticeably darker from outside, but the driver can still see clearly at night. One of the most common state limits for front side windows.
- 20% VLT. Dark enough that reading interior details from outside takes some effort. Often legal only on rear windows of passenger cars, or on any window behind the driver on SUVs.
- 5% VLT. Essentially opaque from outside. Legal on rear windows in only a handful of states, and almost never legal on front side windows.
One detail trips up a lot of drivers. VLT measures what passes through the glass and the film combined, not just the film. Factory glass already blocks some light on its own, typically transmitting around 70% to 80%. Apply a film rated at 50% VLT to glass that transmits 75%, and the combined reading lands closer to 38%, not 50%. A good installer measures the final combined number against your state’s limit, not the standalone film rating.
The Federal 70% Floor
Federal Motor Vehicle Safety Standard No. 205 sets the national baseline. All glazing in areas “requisite for driving visibility” must transmit at least 70% of light. That covers the windshield and the windows immediately to the driver’s left and right. States can impose stricter rules, but they cannot go below 70% on those windows.
The one exception on the windshield is the shade band along the top. Manufacturers can install a tinted strip above the AS-1 line, a marking etched into the glass showing where the 70% transmittance zone begins. If your windshield has an AS-1 line, you can apply non-reflective tint above it. If no AS-1 line is marked, the entire windshield must meet the 70% standard. Some states skip the AS-1 reference altogether and define the strip by inches from the top edge, commonly four, five, or six inches.
How Limits Change by Window Position
Below the federal floor, every state writes its own rules, and they almost always divide the vehicle into four zones: windshield, front side windows, rear side windows, and back window. The pattern across states is consistent even though the exact numbers vary. The closer a window sits to the driver’s line of sight, the less tint is allowed.
Windshield
Nearly every state restricts windshield tint to a non-reflective strip along the top edge, defined either by the AS-1 line or by a fixed number of inches, whichever is more restrictive. Red, yellow, and amber tints on the strip are almost universally prohibited because those colors can be confused with brake lights, turn signals, and emergency vehicle lighting.
Front Side Windows
Front side windows see the widest range of state limits. Common minimums include 70%, 50%, and 35% VLT, with a few states dropping as low as 28% or 25%. This is the window position most likely to draw a traffic stop, because an officer can judge it at a glance.
Rear Side Windows and Back Window
Most states are substantially more lenient on the back half of the vehicle. Many allow any darkness on the rear side windows and back window, especially on SUVs, vans, and trucks. Passenger sedans typically face a minimum, but it’s almost always lower than the front side limit. A common pattern lets you run any tint on the back window as long as the vehicle has side mirrors on both sides.
Sedans Are Treated Differently From SUVs and Trucks
Most states apply different tint limits to passenger cars (sedans and coupes) than to multi-purpose vehicles (SUVs, minivans, and pickup trucks). The general pattern: sedans must meet the posted VLT minimum on all side and rear windows, while SUVs and trucks get a pass on windows behind the driver, often with no minimum darkness restriction at all.
The reasoning is partly about design and partly about use. Multi-purpose vehicles already have smaller rear windows and different sight lines, and they commonly carry cargo that blocks the rear view anyway. Regulators treat dark rear glass as a smaller safety concern when dual side mirrors handle the lost visibility.
Factory Privacy Glass vs. Aftermarket Film
Most tint laws regulate film you apply after purchase, not the glass the manufacturer installs at the factory. Factory privacy glass on rear windows typically falls between 14% and 23% VLT depending on the brand and model, and it ships legal because it’s original equipment. The same VLT achieved with aftermarket film on a front side window would be illegal in every state.
Confusion sets in when drivers add aftermarket film on top of factory privacy glass. Layering a 35% film over rear glass that already transmits only 20% of light drops the combined VLT to roughly 7%, dark enough to limit visibility from inside. If your state has a rear window minimum, that combined reading is what enforcement measures.
Factory privacy glass on the rear also does nothing for your obligations up front. Any aftermarket film on the front side windows that pushes VLT below your state’s minimum is a violation, no matter what the factory installed on the back half of the vehicle.
Color and Reflectivity Rules
Darkness isn’t the only thing states regulate. You can have perfectly legal VLT and still get cited for the wrong color or too much mirror effect.
Red, amber, and yellow films are banned in the vast majority of states because they overlap with vehicle signaling and emergency lighting. A handful of states ban additional colors. Oregon and Washington prohibit green and black films. Blue is restricted in a few states to avoid confusion with law enforcement lighting, though less consistently than red and amber. Neutral gray, charcoal, or smoke-colored film is the safest cross-state choice.
Reflectivity gets its own treatment. Highly reflective “mirror” tint can blind oncoming drivers at night when headlights hit the glass. Some states cap reflectivity at a percentage (limits range from 20% to 35%), and others, including Illinois and Maine, simply require all tint to be non-reflective. About nine states explicitly ban metallic or mirrored finishes regardless of the percentage. Ceramic and carbon films generally stay under reflectivity limits because they reject heat by absorption rather than reflection.
The Dual Side Mirror Requirement
If you tint or otherwise obstruct your rear window, roughly 32 states require the vehicle to have exterior mirrors on both sides. Most modern cars ship with dual mirrors from the factory, so this rarely becomes an issue. On older vehicles with only a driver-side mirror, though, tinting the back window means adding a passenger-side mirror to stay compliant. The rule exists because tinted rear glass reduces the usefulness of the interior rearview mirror.
Medical Exemptions for Darker Tint
Medical exemptions are a state-level program, not a federal one. If you have a condition that makes you unusually sensitive to light, such as lupus, severe photosensitivity, or certain eye conditions, your state may allow you to run darker film than the standard limit. The process varies, but a few elements show up across most states that offer exemptions:
- A letter from a licensed physician or optometrist on their letterhead, explaining why standard tint levels or clear UV-blocking film won’t adequately address the condition.
- An application to a state agency, routed in some states through the DMV and in others through law enforcement agencies like the Department of Public Safety.
- An expiration date. Most permits aren’t permanent, and some are tied to the vehicle’s registration rather than to the driver, which means reapplying if you change cars.
- Proof kept inside the vehicle. Officers have no way to know about your exemption during a stop unless you can show the paperwork.
Not every condition qualifies. States commonly reject applications where UV-blocking eyewear or clear film blocking 99% of ultraviolet light would address the issue without reducing visible light transmission. Applications based on family history alone, with no current diagnosis, are also frequently denied.
How Officers Measure Tint and What Violations Cost
Enforcement uses handheld photometers, sometimes called tint meters. The device clamps onto the window and reads the combined VLT, replacing visual guesswork with a number. These meters carry a tolerance of roughly plus or minus two percentage points, so a 33% reading could mean an actual VLT anywhere from 31% to 35%. If your state’s limit is 35%, a 33% reading might technically still be compliant, but not every officer or court will treat the tolerance in your favor. A few points of cushion above the minimum is practical insurance.
Enforcement timing varies. Some states check tint during annual vehicle inspections, so illegal film means a failed inspection and a registration that can’t be renewed until the tint is fixed. Others check only during traffic stops. A few have started adding tint verification at emissions testing stations.
Consequences escalate with repeat offenses. A first violation often draws a fix-it ticket, giving you a defined period to remove or replace the film and get re-inspected; clearing it can reduce or waive the fine. Ignore the ticket or get caught again, and you’ll typically see a standard traffic citation. Fines generally fall between about $25 for an initial corrective notice and $200 or more for repeat violations, and a few states classify persistent non-compliance as a misdemeanor. Professional removal of illegal film usually runs $50 to $150, and re-tinting to a legal level runs $150 to $450 for a standard sedan.
Checking Your State Before You Install
Because every state publishes its own VLT minimums, color restrictions, reflectivity caps, and vehicle-class distinctions, the only reliable way to know what’s legal on your car is to check your state’s specific rules before buying film. Ask the installer to confirm the combined VLT reading on the finished window rather than relying on the film’s standalone rating, and keep documentation of the installed VLT in case you’re pulled over or inspected. If you need darker tint for a medical reason, apply for the exemption first and keep the paperwork in the vehicle.