Tint rules
Window tint percentage: what the number on the film really means
Enter your glass and the film you are considering: the tool multiplies them and shows the reading a meter would give, the figure every state law is written against.
Real percentage of stacked layers
Combined VLT (what a meter reads)
26.2%
| Light blocked | 73.8% |
| Below the film alone | 8.8% |
| Formula | 75 × 35 / 100 |
A window tint percentage is the share of visible light that a film lets through, called visible light transmission or VLT. A 5% film lets through 5% of the light and is very dark; a 70% film lets through 70% and is barely visible. The number on the box describes the film alone. Once it sits on a window, the light passes through the glass and the film in turn, so the window's reading is the product of the two: a 35% film on 75% factory glass reads 26.2%, and a 20% film on the same glass reads 15%. State laws set a minimum for that combined reading in most cases, which is why the same film can be legal on one car and illegal on another. Some shops quote darkness instead, the share of light blocked: "80% tint" in that sense is a 20% film. The chart below gives the combined reading of common films on two glass readings and the number of the 51 jurisdictions where each one passes on a car's front side windows.
From "% dark" to VLT
VLT of that film
20%
| On 70% glass | 14% |
| States where it passes in front (car) | 0 / 51 |
Statutes read by Radif Partners · Editorial policy · How the check works
Tint percentage chart
Each row is a common film. The middle columns give the window's reading once the film is on glass that transmits 70% (the federal minimum for new glass in the driver's view) or 85%. The last two columns count the jurisdictions, out of 51, where that film passes on a car's front side windows and back window when applied to 75% glass, with any written tolerance counted.
| Film VLT | Darkness | On 70% glass | On 85% glass | Front doors pass | Back window pass |
|---|---|---|---|---|---|
| 5% | 95% | 3.5% | 4.3% | 0 / 51 | 18 / 51 |
| 15% | 85% | 10.5% | 12.8% | 0 / 51 | 20 / 51 |
| 20% | 80% | 14% | 17% | 0 / 51 | 24 / 51 |
| 35% | 65% | 24.5% | 29.8% | 9 / 51 | 28 / 51 |
| 50% | 50% | 35% | 42.5% | 35 / 51 | 47 / 51 |
| 70% | 30% | 49% | 59.5% | 40 / 51 | 49 / 51 |
| 80% | 20% | 56% | 68% | 40 / 51 | 49 / 51 |
Transmission or darkness
The laws speak of transmission, the light that passes. Many shops and online listings speak of darkness, the light blocked, and some use both on the same page. A "35% tint" can therefore mean a 35% film or a 65% one. Convert any advertised number before you buy:
From "% dark" to VLT
VLT of that film
20%
| On 70% glass | 14% |
| States where it passes in front (car) | 0 / 51 |
Why factory glass changes the result
Federal standard FMVSS 205 sets 70% as the minimum light transmittance for glass needed for driving visibility, and the windows of new cars are built to meet it. Many cars also come with darker privacy glass behind the driver, which is allowed because those windows are not requisite for driving visibility. When you add film, the reading of the window is the glass multiplied by the film. The federal regulator has written that adding film can take a window below the federal level (NHTSA interpretation), and state laws then decide what is allowed.
Percentages on the windshield
The windshield follows its own rule in every state. Most allow a strip of film along the top only, measured in inches or down to the AS-1 line printed on the glass, and the percentage of that strip is often not limited at all. A few states set a percentage for the whole windshield instead, usually 70%. A tint percentage bought for the side windows therefore says nothing about the windshield; the windshield guide gives the rule for each state.
How to read your own window
A tint meter, which many film shops and some inspection stations own, clamps over the glass and gives the combined reading in a second. Measure the bare glass first, before the film goes on, and keep the figure: it lets you compute the darkest legal film for your car with the legal percentage table. If the car already has film, the meter reads glass and film together, which is what an officer would see.
Common films and where they end up
On 75% glass, very dark films, 5% to 15%, are legal on the front side windows of a car in no state, and on the back window only where the law sets no number or a very low one. 20% film fails on the front everywhere once the glass is counted, even under New Mexico's 20% limit read cautiously. 35% film is a frequent request, yet on that glass it passes on the front only in the 9 states whose limit is lower, and fails in every state that sets 35%. 50% and 70% films pass on the front in most states, and only clear film passes in the states that ask for 70% total. Check the state-by-state groups for the exact limits.