How Strong Is A Car Windshield?

How strong is a windshield

It is a common misconception that auto glass is fragile. In fact, a flawless fiber of glass pulled lengthwise is five times stronger than steel! Although glass is quite strong and resistant to breaking, its brittleness does explain why it breaks so easily. But the windshields in cars are more resistant to breaking than regular glass.


What Makes A Car Windshield So Tough?

There are two methods for strengthening glass: tempering and laminating. Tempered glass is first heated just below its melting point, then exposed to bursts of cold air. The cold cools and shrinks the glass’s surface faster than its inside, compressing the surface inward.

Tempered glass is made by reheating it to a high temperature and then rapidly cooling it. This process makes the surface dense, which makes it stronger so it takes more force to break it. Tempered glass shatters into small pieces rather than large, sharp shards. If you’ve seen little squares of a car windshield scattered on the street, you’ve seen how tempered glass shatters.


What Is The Science Behind A Car Windshield?

The main function of a car windshield is to protect the vehicle’s occupants from injury. It does this by providing a barrier between them and the environment. The windshield’s ability to do so depends on the strength of the glass used in its construction.

Modern car windshields are typically made of laminated safety glass. The two outer layers of a laminated windshield are made of annealed glass sheets, while the middle layer is a special strip of Polyvinyl Butyral (PBV) that holds the two panes together. If the windshield breaks, broken shards will not fly off on impact but remain stuck to the special PVB interlayer. In essence, this is what makes modern car windshields more secure and safe against damaging elements.


Why Is A Windshield So Important?

Modern automobile windshields are capable of withstanding impacts and protecting drivers by serving multiple safety functions:

1. Protection

Windscreens of cars act as shields against high-velocity wind loads, preventing the car from being turned on its side. This gives us an idea of how strong windscreen glass must be. Additionally, they protect against other external elements like wind-borne debris, hailstones, dirt, etc., with great effect in safeguarding the lives of passengers; more so those sitting in the front seats.

2. Structural Support

The windshield of a car does not merely complete the look of the vehicle. Though it is true that sans the windshield glass, your car would look quite odd and a bit odd, it is the fact that it prevents the car’s roof from caving in, even when you have an accident which makes it a crucial component.

In a front-end collision, the windshield provides 45% of the car’s structural integrity; in a rollover accident, 60%. The windshield’s ability to absorb impact has often saved lives by preventing passengers from being crushed by the collapsing roof.

3. Airbag Deployment

In the past, death was a common occurrence for passengers who were not restrained in automobiles. Modern cars have special airbag safety systems to cushion passengers and prevent injuries in the case of a crash. However, this airbag system relies on a strong windshield to function effectively.

A weakened windshield, improperly installed or made of low-quality glass, will fail to provide proper airbag support, leaving passengers vulnerable in the case of a sudden head-on collision.

4. Prevention Of Passenger Ejection

Research has shown that defective seat belts are a leading cause of passenger ejection in case of a sudden impact. The windshield is responsible for keeping passengers from being thrown out of the vehicle; however, only a strong and top-shaped windshield can adequately perform this function.

In addition, even if the windshield does get some damage or breaks owing to the intensity of an accident and the speed of a vehicle, it will not cause any major injuries – intrinsically, windshield glass pieces remain stuck to a special interlayer made of PVB and do not scatter around.



For safety, a car windshield is a modern marvel. It’s built to withstand impact, and many cars now have windshields that are part of the car’s safety system—airbags, seatbelts, and windshields work together to protect the driver in an accident.

Are you looking for windshield repair or replacement services near you? Contact GlassFixit now.

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