Window tint percentages explained: 5%, 20%, 35%, 50% and 70%
A lower window tint percentage means less visible light gets through. A window measured at 20% lets through less light than one measured at 35%. The number describes light transmission. It does not mean the percentage of light blocked.
That distinction makes shopping easier. There is one more thing to check: does the number describe a roll of film, a laboratory test on glass, or the finished window on your car? Those numbers are not always the same.
By Window Tint Laws · Research and review standards
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What does VLT mean?
VLT stands for visible light transmission. Imagine 100 equal units of visible light reaching a window. If 70 get through, its VLT is 70%. If five get through, its VLT is 5%.
These examples explain the scale:
| Measured VLT | Light that gets through | Relative appearance |
|---|---|---|
| 5% | 5 out of 100 units | Very dark |
| 20% | 20 out of 100 units | Dark |
| 35% | 35 out of 100 units | Lighter than 20% |
| 50% | Half of the light | Lighter than 35% |
| 70% | 70 out of 100 units | Lighter than 50% |
The appearance column is a general comparison, not a picture of your future windows. The cabin, weather and viewing angle can change how a window looks.
Product names and test configurations are not interchangeable.
Sources: 3M Automotive Window Film Crystalline Series Technical Data Sheet, Revision E (May 2024), TC1800 TINT-CHEK Window Tint Meter Manual
Continue: Tint planner
Is 20% tint darker than 35% tint?
Yes, if both numbers describe the same kind of measurement. A finished window at 20% passes less visible light than a finished window at 35%.
This does not tell you which option is legal for your front doors or comfortable for your driving. It also does not prove which product rejects more solar heat. Darkness, heat performance and legal permission answer different questions.
When comparing two quotes, ask for the product name and shade. If the numbers seem different, ask whether each is a film label or a finished-window estimate. You do not need to buy a meter to request a price.
Optical transmission is not a universal visibility or safety threshold.
Sources: The Effects of Motor Vehicle Window Tinting on Traffic Safety and Enforcement (February 1994), 3M Automotive Window Film Crystalline Series Technical Data Sheet, Revision E (May 2024)
Does 35% film make a 35% finished window?
Not automatically. The existing glass already changes how much light gets through. Product names can also be rounded labels rather than exact measurements.
Some technical sheets report film tested on a specific pane of glass. For example, the linked 3M sheet gives separate tables for two reference glasses. That makes the test glass part of the result. It is not a measurement of every vehicle that later receives that film.
If an inspection or legal limit matters, have the actual finished window checked. Keep that result separate from the product’s name.
Do not multiply a glass-inclusive published value by glass transmission again.
Sources: 3M Automotive Window Film Crystalline Series Technical Data Sheet, Revision E (May 2024), TC1800 TINT-CHEK Window Tint Meter Manual
Continue: Tint planner
How do glass and film percentages combine?
For a simple estimate, multiply the glass percentage by a true film-only percentage, then divide by 100.
For example, hypothetical 80% glass with true 35% film-only transmission gives 28%: 80 × 35 ÷ 100 = 28.
Do not enter a number that already includes test glass as though it describes film alone. That would count glass twice. If you do not know what the supplier’s number measures, ask before using the tint calculator.
Using different hypothetical inputs, 70 × 50 ÷ 100 gives 35%. An idealized 100 × 35 ÷ 100 also gives 35%, but 100% is not an assumed factory-glass reading. In decimal form, the first example is 0.80 × 0.35 = 0.28.
Multiplication is a simplified estimate requiring film-only input.
Sources: 3M Automotive Window Film Crystalline Series Technical Data Sheet, Revision E (May 2024), TC1800 TINT-CHEK Window Tint Meter Manual
Continue: Tint planner
Which tint percentage is legal?
There is no single percentage that answers that question for every window. Start with your state, vehicle category and the exact window. The windshield, front doors and rear windows may have different rules. Color, reflectance and paperwork can matter too.
Use the state-law directory to find the applicable guide. Read its qualifications before choosing a film from a chart.
Sources: 3M Automotive Window Film Crystalline Series Technical Data Sheet, Rev E, May 2024, TC1800 TINT-CHEK Window Tint Meter Manual, Tinted Windows, Canon: How exposure changes a photograph’s brightness
Can a photo reliably show tint darkness?
A photo can help you choose a look, but it cannot give you an exact VLT reading. Camera exposure and bright surroundings can make the same window look different. An outside photo also cannot show everything a driver will see after dark.
Use photos for appearance ideas. Use product information and actual measurements for numbers. If you are concerned about night visibility, discuss that before installation rather than assuming the darkest lawful option will suit you.
Sources: Automotive Window Tint Frequently Asked Questions, TC1800 TINT-CHEK Window Tint Meter Manual
Common questions
Does 20% tint block 20% of the light?
No. A measured 20% VLT window lets about 20% of visible light through. That is why it is darker than a window measured at 35%.
Is 70% tint almost clear?
It transmits much more visible light than 20% or 5% when compared on the same basis. “Almost clear” is an appearance description, however. It does not establish that a particular installation is permitted.
Should every window have the same percentage?
Not necessarily. Windows can have different starting glass and different legal requirements. Ask about each window rather than choosing one number for the entire vehicle.