Tires & Detailing · Free tool
Free Window Tint Law Checker
Enter your glass, the film you want and your state’s limit. The checker works out the tint percentage you will actually end up with and whether it passes.
- Free to use
- No signup
- Runs in your browser
The window
Factory glass already blocks some light. A tint shop can measure yours with a meter.
Common film shades
Your state’s limit
Limits differ by state and by window. Look yours up, then enter it here.
Net light transmission
26% VLT
75% glass × 35% film.
Enter your state’s limit to check this combination against it.
- Light blocked
- 74%
- Darkest film that stays legal
- —
A meter reading at the roadside is what counts. Leave a margin, because meters and film batches vary by a few points.
A calculation from the figures you enter, not legal advice. Read the disclaimer. Updated .
02Your result
What your window tint result means
The percentage on the film box is not the percentage on your window. The glass under it counts too.
- 01
Net light transmission
The share of visible light that gets through the glass and the film together. This is the figure a tint meter reads.
- 02
Legal or not
Whether the net figure meets the minimum you entered. A lower VLT number means a darker window.
- 03
Darkest legal film
The darkest film that keeps this window on the right side of your limit, given the glass you started with.
What to do next
Understand tint percentages
What 5%, 20%, 35% and 50% look like, and the film types and prices.
Window tint guidePrice the rest of the job
Typical costs for a detail or a ceramic coating.
Detailing cost estimatorFind your state’s limit
The International Window Film Association keeps a summary of state tint laws.
Where to look it up
03How it works
The window tint (net VLT) formula
Light has to pass through the glass and then the film, so each takes its share and the two percentages multiply.
Net VLT (%) = glass VLT (%) × film VLT (%) ÷ 100
Darkest legal film VLT (%) = state limit (%) ÷ glass VLT (%) × 100
Round up to the next lighter film you can buy, and leave a margin.
What each term means
- VLT
- Visible light transmission: the share of visible light that passes through.
- glass
- The VLT of the window before any film is added.
- film
- The VLT rating of the tint film.
- limit
- The minimum VLT your state allows for that window.
What the tool assumes
- One layer of film on glass with the VLT you enter.
- Your state’s limit applies to film and glass combined (net VLT). Check whether yours is stated that way.
- The limit you enter is the right one for that window. Front, rear and windshield limits usually differ.
- No allowance for meter tolerance, so leave a few points of margin.
04Worked example
Window tint example: 35% film on factory glass
A 35% film on a front window whose factory glass lets through 75% of visible light, in a state with a 35% limit.
- 01
Multiply the two percentages
75% glass × 35% film ÷ 100
26.3% VLT
- 02
Compare with the limit
26.3% against a 35% minimum
Too dark
- 03
Find the darkest legal film
35% limit ÷ 75% glass × 100
46.7%
- 04
Pick the next film up
The nearest common shade lighter than that
50% film
- 05
Check it
75% × 50% ÷ 100
37.5% VLT
Net VLT with a 35% film
26%
A film sold as 35% fails a 35% limit on this glass. A 50% film gives 37.5%, which passes with room to spare.
Try your own numbers05Background
How window tint laws work
Tint is measured as visible light transmission, or VLT. The International Window Film Association defines it as the visible light portion of the solar spectrum that passes through the glass. A lower number means a darker window.
| Layer | What it sets |
|---|---|
| Federal standard | New vehicles must have at least 70% light transmittance in glazing needed for driving visibility. The AS-1 line marks the part of a windshield that may be darker. |
| State law | The limits for film fitted after the car is sold. They differ by state and usually by window: front sides, rear sides, rear window and windshield. |
| Exemptions | Some states allow darker tint for medical reasons, on application. New York’s DMV, for example, has an exemption form. |
Factory glass is not clear. The federal standard allows it to be as dark as 70%, and most is slightly lighter than that, which is why a film rated at exactly your state’s limit usually ends up darker than the limit once it is on the car. Multiply the two percentages to see the result.
For film types and what tinting costs, see the window tint section of the detailing guide.
06When to use it
When to use a window tint checker
Before the film goes on. It is easier to choose the right shade than to have the wrong one removed.
Before you buy film
Find the darkest shade that will still pass on your glass.
To check a shop’s quote
Make sure the film they propose is legal on the window they propose it for.
Buying a tinted used car
Work out whether the tint already fitted is likely to be legal where you live.
After moving state
Test your existing tint against the new state’s limit.
Mistakes to avoid.
- Assuming a 35% film gives a 35% window. On factory glass it is darker.
- Using the rear window limit for the front side windows.
- Relying on an old summary chart instead of the current state law.
- Leaving no margin. A roadside meter reading can differ slightly from the rating on the film.
07Related guides and tools
Keep going from here.
Guides that go with this tool
Related tools
08Questions
Window Tint Law Checker: your questions.
What does tint percentage mean?
It is the visible light transmission, or VLT: the share of visible light that passes through the window. A 35% tint lets 35% of light through. The lower the number, the darker the window.
How do I calculate window tint percentage?
Multiply the VLT of the glass by the VLT of the film and divide by 100. A 35% film on glass that passes 75% of light gives 26.25%, not 35%.
Is 35% tint legal?
It depends on the state and the window. Limits differ from state to state and usually between front and rear windows. Remember that a 35% film on factory glass measures darker than 35%.
What is the AS-1 line on a windshield?
It is a marking on the windshield. Under the federal glazing standard it marks the area that has less than 70% light transmittance, usually a shade band along the top. If there is no AS-1 line, the whole windshield must meet 70%.
Can I get a medical exemption for darker tint?
Some states offer one. New York, for example, lets drivers apply for an exemption through its DMV. Check with your own state’s motor vehicle agency.
09Estimates and sources
Read this before you rely on it.
Built and checked by CarTipsMentor Team. Last updated . How we check our work.
Sources
- [1]International Window Film Association, Interactive Tint Laws
- [2]International Window Film Association, Automotive Education Guide 2026
- [3]National Highway Traffic Safety Administration, Interpretation letter on FMVSS No. 205 glazing and the AS-1 line (May 2011)
- [4]Rayno Window Film (manufacturer), Window Tint Percentages: Examples and What You Need to Know
- [5]New York State Department of Motor Vehicles, Tinted Windows