3 Life Saving Tricks to Break Glass Using a Pocket Knife

Even with a glass breaker, breaking into or out of a car can be counter-intuitive. In the event of an emergency there’s no time to learn by trial and error – luckily, there are three simple tricks that make it doable.

1. Ignore the windshield and target one of the side windows

Windshields are made from sheets of annealed glass bonded to transparent plastic, when they do shatter they are made to hold together instead of sending shards flying into the vehicle. “The next time you need to escape from a car window, remember that the windshield is annealed and it’s going to hold together,” said Destin Sandlin, creator of popular YouTube channel Smarter Every Day. As Destin explains, car manufacturers make windshields and side windows out of two different kinds of glass for good reason. “When annealed glass breaks, not only is the cracking slow, but sometimes it doesn’t even make it to the other side of the glass, which is good for windshields,” says Sandlin.

2. Find the pointiest part of either end of your pocket knife’s handle

You need a strong, pointed object to break the tempered glass used in the side windows of cars, Brian Brushwood explains on National Geographic’s Hacking the System. Even without a glass breaker, your pocket knife may still be the strongest, pointiest impact tool that is readily available. If this is the case, find the pointiest end of your knife handle to impact the glass. Keeping the knife in the closed position, choke up on the opposite end of the handle for the maximum force. “The safety glass is made to withstand blunt forces, but not the focused energy and force from a pointed object,” Brushwood says.

3. Strike as close to the edge of the window as possible – NOT the center

Swing a hammer at the middle of a tempered glass window, and it will bounce right off.  “It’s designed to be very, very strong at the center, but not on the edge,” explains Sandlin. In this YouTube video Sandlin demonstrates just how fast tempered glass breaks when you target the edges.

Knife featured in image: Kershaw Blur Glassbreaker