A window tint calculator helps you determine the final darkness of your car windows when adding aftermarket tint film to factory glass. Since factory glass already blocks some light, the combined VLT (Visible Light Transmission) is always darker than the tint film alone. This tool calculates your combined VLT and checks whether your tint setup is legal in your state for each window position.
Combined VLT Calculator
Most front side windows are 70-78% VLT from the factory.
Tint on Your Car
Visual representation of your selected tint on different window positions.
Tint Darkness Comparison
See how different VLT percentages look. Lower VLT = darker tint.
State Tint Legality Check
Tint laws change frequently. Always verify current regulations with your state DMV or local law enforcement before installing tint.
Tint Level Benefits Guide
| VLT% | Name | UV Block | Heat Reduction | Privacy | Night Visibility |
|---|---|---|---|---|---|
| 70% | Barely visible | 99% | Low | Minimal | Excellent |
| 50% | Light tint | 99% | Moderate | Slight | Good |
| 35% | Medium tint | 99% | Good | Moderate | Fair |
| 20% | Dark tint | 99% | High | Good | Reduced |
| 15% | Very dark | 99% | Very high | High | Poor |
| 5% | Limo tint | 99% | Maximum | Maximum | Very poor |
How to Use the Window Tint Calculator
Choosing the right window tint for your car involves more than picking a shade you like. You need to account for the light your factory glass already blocks, understand how VLT percentages combine, and make sure your final tint level is legal in your state. This calculator handles all of that in seconds.
Step 1: Select Your Factory Glass VLT
Start by choosing the VLT percentage of your existing factory glass. Most modern cars have front side windows at 70-78% VLT, meaning the glass lets through 70-78% of visible light even before any aftermarket tint. SUVs and trucks often come with darker factory tint on rear windows, sometimes as low as 15-25% VLT. If you are unsure of your factory glass VLT, 75% is a safe default for front windows.
Step 2: Choose Your Tint Film
Select the VLT percentage of the tint film you plan to install. Common options range from 70% (barely visible, mostly for UV protection) down to 5% (limo tint, nearly opaque). The most popular choices for a good balance of style and visibility are 35% and 20%. You can also enter custom values if your tint shop offers non-standard percentages.
Step 3: Review Combined VLT
Click "Calculate Combined VLT" to see your effective window darkness. The formula is straightforward: combined VLT equals factory glass VLT multiplied by tint film VLT, divided by 100. For example, putting 35% tint film on 75% factory glass gives you a combined VLT of about 26%. The visual preview shows you approximately how dark the finished window will appear, and the car diagram updates to show the tint on each window position.
Step 4: Check State Legality
Select your state from the dropdown to see the minimum VLT allowed for front side windows, rear side windows, and the rear window. The window tint calculator instantly shows a pass or fail badge for each window position based on your calculated combined VLT. Most states have stricter limits on front side windows (typically 25-70% VLT) and more relaxed rules for rear windows. Some states allow any darkness on rear windows as long as the vehicle has side mirrors.
Understanding VLT Percentages
VLT stands for Visible Light Transmission and measures the percentage of visible light that passes through your window. A 5% VLT window only lets through 5% of light, blocking 95% — this is the darkest legal tint in most states, and only for rear windows. A 70% VLT window lets through 70% of light, appearing nearly clear. Quality tint films of all VLT levels block approximately 99% of harmful UV rays, so even a light tint provides significant sun protection for your skin and your car's interior.
Important Considerations
Window tint laws vary by state and can change. Always verify current regulations with your state DMV or a licensed tint installer before getting your windows tinted. Some states also have additional rules about tint reflectivity, colors allowed, and medical exemptions. Keep in mind that if you drive across state lines, you must comply with the tint laws of the state you are in, not just your home state.
Frequently Asked Questions
Is this window tint calculator really free?
Yes, this window tint calculator is completely free with no signup required. All calculations run locally in your browser. No data is stored or transmitted anywhere.
Is my data safe when using this tool?
Absolutely. Everything is calculated in your browser using JavaScript. No personal information or vehicle data is ever sent to a server. Your privacy is fully protected.
How is combined VLT calculated when stacking tint on factory glass?
Combined VLT is calculated by multiplying the factory glass VLT by the tint film VLT and dividing by 100. For example, 70% factory glass with 20% tint film gives 14% combined VLT (70 x 20 / 100 = 14%). This is because each layer blocks a percentage of the remaining light.
What VLT percentage is factory glass on most cars?
Most modern vehicles have factory windshield glass at about 70-75% VLT. Front side windows are typically 70-78% VLT. Rear windows may already have factory tint at 15-25% VLT on many SUVs and trucks. Check your vehicle manual for exact values.
What does VLT stand for in window tinting?
VLT stands for Visible Light Transmission. It measures the percentage of visible light that passes through the glass. A lower VLT means a darker tint — 5% VLT (limo tint) blocks 95% of visible light, while 70% VLT lets through 70% of light.
Can I get a ticket for illegal window tint?
Yes, driving with window tint darker than your state's legal limit can result in a fix-it ticket, fine, or even a failed vehicle inspection. Penalties vary by state. Some states are stricter about front windows while allowing darker tint on rear windows.
Does window tint block UV rays?
Yes, most quality window tint films block 99% of UV rays regardless of VLT percentage. Even a light 70% VLT film provides significant UV protection. This helps protect your skin and prevents interior fading of upholstery and dashboard materials.
Are window tint laws the same in every state?
No, window tint laws vary significantly by state. Some states like California require 70% VLT on front windows, while others like Texas allow 25%. Many states have different limits for front side windows versus rear windows. Always verify current laws with your local DMV.