What is the AS-1 line on a windshield?
Reviewed by the Skyview Auto Glass technical team — NWRD-, ASE- and DINITROL-trained technicians · Updated November 2026
Quick answer
The AS-1 line is a small mark, usually etched near the top edge of the windshield, that shows how far down a shade band or tint strip may come. Anything below that line is considered the driver’s viewing area. The exact tint rules below it vary by state, so check the rules for the state where the vehicle is registered.
What the AS-1 line marks
Look near the top edge of the windshield and you will often find the letters AS-1 or AS1 etched into the glass, with a line running across the pane. That line marks the lowest point a factory shade band or an aftermarket tint strip may reach. Below it is the area the driver looks through, and the rules for tinting that area are stricter.
The mark refers to a glass standard for light transmission, and the line itself is a guide for how much of the top of the windshield may carry a darker band. A factory shade band sits above the line on many vehicles, fading from dark at the top to clear below it.
Tint rules below the line vary by state
The AS-1 line marks the boundary, but the tint rules below it are set by each state. Some allow a strip above the line and nothing below; others set different limits. Check the rules for the state where the vehicle is registered before adding any tint.
Where to find the AS-1 line
- Etched into the glass near the top edge, often in a corner.
- Marked with the letters AS-1 or AS1 beside the line.
- A faint horizontal line running across the top of the windshield.
- Sometimes paired with the glass maker’s code and the DOT number.
More questions about the AS-1 line
Can you tint above the AS-1 line?
A shade band or tint strip above the AS-1 line is allowed in many states, since that area is above the driver’s main view. The exact rules vary by state, so check before adding a strip.
Can you tint a windshield below the AS-1 line?
Tinting the windshield below the AS-1 line is restricted in most states because that is the driver’s viewing area. The limits vary by state, so check the rules where the vehicle is registered.
Where is the AS-1 line?
It is etched near the top edge of the windshield, usually marked with the letters AS-1 or AS1 beside a faint horizontal line across the glass.
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