The number is transmission, not blockage
VLT stands for Visible Light Transmission: the percentage of visible light that passes through. Higher is lighter. 70% VLT lets 70% of light through and is nearly clear. 5% VLT — "limo" — lets almost nothing through.
People routinely invert this and ask for "70% tint" meaning dark. Say what you want in plain words as well as in numbers.
Film VLT versus net VLT
This is where quotes go wrong. Factory automotive glass is not perfectly clear — it typically transmits somewhere around 75 to 85% on its own. The law measures the combination of glass and film.
So a 70% film on 80% factory glass gives roughly 56% net, which is below California's 70% front-window limit. A shop that promises "legal 70% film" on your front doors without accounting for the glass is promising you a measurement that will not pass.
Getting a legal front window means choosing film that leaves the combination at or above 70%, which in practice means a very light film indeed.
Measuring it
Officers use a handheld meter that clamps over the glass and reads the combination directly. It takes seconds and there is no arguing with it.
A reputable installer has one too, and will measure your factory glass before recommending film for the front doors.
Need this done rather than explained? There is no shop to drive to. We come to wherever your car already is — your driveway, your workplace car park, an apartment lot, or the side of the road it stopped on — anywhere in greater Sacramento, with no call-out fee and no mileage charge. Give us the year, make and model and you will have a firm price before the call ends.