Free tool · compliance
Net VLT calculator
A tint meter does not read your film. It reads the film and the factory glass together, and the two multiply: film % × glass % ÷ 100. That is why 20% film on tinted OEM glass reads about 14%, and why a job that looked legal on paper fails at the roadside. Enter both numbers, pick your state, and see it per window.
Your numbers
Film VLT is the number on the box. Factory glass is usually 70–75% on tinted privacy glass and 78–80% on clear glass — if you have a meter, read the bare glass and use that.
70 for tinted OEM glass, 80 for clear
Net VLT 14% 20% film × 70% glass ÷ 100
Common shades on this glass
Pass/fail compares net VLT against that state's stated minimum for each window. Some states apply a measurement tolerance and some state no limit at all for the glass behind the driver — the state page says which. None of this replaces a meter reading on your own glass.
What the numbers mean
Why it multiplies
Each layer passes a fraction of the light that hits it. Glass at 70% passes 0.70, film at 20% passes 0.20, and the light that makes it through both is 0.70 × 0.20 = 0.14 — 14%. Percentages of percentages multiply; they never subtract.
So the darker your factory glass already is, the lighter the film has to be to hit the same legal number. On privacy glass behind the driver, film that reads 5% on a meter is common without anyone installing 5% film.
Pass, fail, no limit stated
State limits are minimums: the window must let at least that much light through, so a lower net VLT is what fails. Pass means your net number is at or above the state's floor for that window.
No limit stated means the statute sets no VLT number for that window — not that anything goes. Not allowed means the state bans aftermarket film on that window outright, whatever its darkness.
Before you cut film
Read the bare glass with a meter if you have one, because 70% is a convention and not a promise: OEM glass varies by model, year and even by window on the same car.
Then read the finished job. A meter reading on the installed window is the only number an officer will care about, and it is the only number that protects you if a customer comes back holding a ticket.
VLT questions
What does 20% tint on 70% glass actually read?
About 14%. Multiply the two percentages and divide by 100: 20 × 70 ÷ 100 = 14. On 80% clear glass the same film reads 16%. This is the single most common reason a job the customer asked for turns out to be illegal on the front doors.
What is the factory glass VLT of my car?
Clear automotive glass is typically 78–80% and factory privacy glass is often in the low 70s or darker, but it varies by manufacturer, model year and window. If accuracy matters — and near a 70% front-side limit it does — put a meter on the bare glass before the film goes on rather than trusting a table.
Is net VLT the same as the number on the film box?
No. The box number is the film measured on its own, on a clear reference. Net VLT is film plus the glass it is going onto, which is what a meter clipped to the window reports. A shop that quotes the box number is quoting a number nobody will ever measure.
Does a state tolerance make a borderline job legal?
Some states publish a measurement tolerance that officers apply to the reading, but it is an allowance for meter error, not extra darkness you are entitled to. Where a state states one, it is listed on that state's page under Measurement tolerance. This calculator compares against the stated limit itself and ignores tolerances on purpose.
Legal disclaimer: general information, not legal advice. Limits come from each state's own statute or DMV page as recorded on our dated tint law pages, laws change, and enforcement practice varies — verify with your DMV or state police before you install film.