About Window Tint Calculator

The most common mistake we see is drivers (and even some shops) confusing a film's rated VLT with the final window VLT. A "20% tint" film applied to factory glass that's already 75% VLT gives you a combined VLT of 15%, well below the legal limit in most states. Nobody warns you about this at the shop counter.

We're automotive enthusiasts and tinting hobbyists who got tired of doing this math on a phone calculator, and tired of watching people get fix-it tickets for tint that seemed legal on the packaging. So we built a tool that handles the formula automatically and flags potential legal issues by window position.

This calculator is free, has no ads in the way of the results, and never asks for your email. That's how it should be.

The VLT formula follows the International Window Film Association (IWFA) standard: Combined VLT = (Film VLT × Factory Glass VLT) ÷ 100. This is the same approach tint installers and state inspection stations use. We don't adjust it or apply any proprietary coefficients, the formula is the formula.

UV blocking estimates follow published IWFA performance data for automotive films with UV inhibitor layers. Heat reduction figures are derived from AAA research on vehicle thermal comfort, tiered by combined VLT level. These are estimates, actual performance depends on film quality and installation technique.

The legal guidance uses commonly observed state DMV limits for each window position. We update these periodically as laws change. This isn't legal advice, state tint laws are enforced at the officer's discretion and can include medical exemptions, but it gives you a solid starting point before installation.

Every piece of content on this site is written by people who actually care about window tinting, not churned out by automation. We verify calculation formulas against IWFA documentation, cross-check state laws with published DMV resources, and review performance claims against third-party test data from sources like AAA and the Skin Cancer Foundation.

When we publish state-specific legal limits, we cite the source and include the date we last checked. Window tint laws do change, California and New York have updated their regulations in recent years, and other states revisit the issue periodically. If you see something outdated or wrong, we want to know.

Blog posts on this site are written to be genuinely useful to someone planning a tint job, not to rank for keywords. If a post doesn't teach you something worth knowing, it doesn't belong here.

We don't sell tint film. We don't take commissions from tint installers. We don't have a preferred brand. The calculator gives you the same numbers whether you're buying ceramic film or a basic dyed kit from a discount store.

We don't provide legal advice. The legal guidance note in your results is a reference point, not a guarantee. If you're getting tint for medical or occupational reasons, consult your state's DMV about exemption processes before installation.

And we don't have a subscription, paywall, or credit system. The window tint VLT calculator is free, always has been, and will stay that way.