Window Tint Percentage Estimator for iPhone

You can get a usable estimate with a phone camera if the reading is anchored to a known light source. TintCheck guides you through backlighting the glass with a free printable reference card and your flashlight, then compares how much light passes through the tint against the reference. The result is an estimated VLT% with a confidence range — a sanity check, not a substitute for a certified meter.

VLT stands for visible light transmission: the percentage of visible light that passes through the glass and film together. A 70% VLT window is quite clear, while a 5% window is the very dark 'limo' tint. Tint laws are written in VLT terms, which is why TintCheck reports its estimates as a VLT percentage.

It means the window lets through about 35 percent of visible light — the lower the number, the darker the tint. Note that the percentage on a roll of film refers to the film alone; once applied over factory glass, the combined VLT of glass plus film is lower. TintCheck estimates the combined result, which is what you actually see and what laws regulate.

A phone can estimate tint, but honesty about the limits matters. Camera readings depend heavily on ambient light, which is why naive point-and-read apps can be wildly off; TintCheck reduces that error with a reference-card calibration step and reports a confidence range instead of a single exact number. For anything official — an inspection or a dispute — only a certified VLT meter counts.

No. Enforcement and inspection use certified, purpose-built VLT meters, and no phone app is a legal substitute for one. TintCheck says this on the result screen itself: readings are estimates for your own information. Its value is knowing roughly where you stand before someone with a certified meter checks.

Legal VLT limits vary by US state and by window position — front side windows are usually held to a lighter standard than rear windows. TintCheck includes a state-by-state reference of commonly cited limits and shows them beside your estimate for context. Laws change and exemptions exist, so verify with an official source or a professional installer before making decisions.

Dark tint on a used car may be below your state's limit, which can mean a fix-it ticket or a film removal bill after purchase. With TintCheck you can estimate each window in the parking lot in a few minutes, log the readings per window with photos, and compare them against your state's commonly cited limits. It is a quick screen that tells you whether to ask harder questions.

Because glass brightness in a camera frame depends on the scene behind it, the weather, and the exposure the phone picks — a naive app turns all that noise straight into a number. TintCheck anchors the reading to a known reference target and a controlled backlight, normalizes the signal, and rejects outliers before showing an estimate. It also refuses to pretend: the result is a range, labeled as an estimate.

The reference card is a free white calibration target you print at home or display on another screen. Placed behind the glass and lit by your flashlight, it gives the camera a known light source to compare against, which is what turns a rough guess into a repeatable estimate. There is no accessory to buy — the card is part of the app.

In most US states, yes: front side windows must typically let in more light than rear side windows or the rear windshield, and windshields usually allow only a top strip. That is why TintCheck logs each window position separately and shows the relevant commonly cited limit next to each one. A car can be within limits in the rear and over them in the front.

TintCheck saves every estimate to the specific window it belongs to, with a timestamp and an optional photo. You can export a simple summary of the whole vehicle to share or print — useful when talking to an installer, documenting a car you are selling, or keeping notes on a car you just bought. All of it stays on your device.

TintCheck runs entirely on the device: the camera estimate, the calibration math, the per-window log and the state limit reference are all local. No account, no upload, no connection needed in a parking garage or on a rural lot. Your readings and photos never leave the phone.