The Fascinating Reason Why Seat Belts Have an Extra Loop of Fabric

We tend to take seat belts for granted, but since the invention of this safety feature, the automotive industry has been coming up with innovative new ways to advance it and keep drivers safer. You may not even think about it other than when the height adjustment is off. Have you ever noticed a small loop of sewn-on fabric on your three-point seat belt? If you’re wondering why there’s a loop on most modern belts, the reason for it is fascinating.

The loop on your seat belt is actually a safety feature

The energy management loop on a Subaru Outback seat belt
Energy management loop on passenger’s side seat belt | Becca Hopkins, MotorBiscuit

That small bit of fabric (that I always thought was just for convenience to stop the belt from banging against the hard plastic near the door) actually serves an important, though minor, purpose. Car safety features come in all shapes and sizes, and this small loop is one of them.

Family Handyman reports that this fabric loop is called an “energy management loop.” It can absorb some of the energy and dissipate some of the impact of an accident. Companies have specifically designed a row of seams on the fabric loop to break under the extreme stress you’d experience in a vehicle collision. 

When you get in an accident, and the seat belt is put under that extreme pressure, the threading in the loops rips, and the loop unfolds. This simple action adds a few extra inches to the belt and can absorb more energy to keep you safer and decrease the risk of injury. 

Why are some driver’s belts different?

Driver's side seat belt with the energy management loop on a 2021 Subaru Outback
Driver’s side seat belt on a 2021 Subaru Outback, with the energy management loop | Becca Hopkins, MotorBiscuit

You may notice a small button near the buckle rather than a loop on the driver’s side belt. There may be a few reasons for this. Family Handyman reports that the lack of a loop is also for safety. Front and rear passengers have more room to fall forward in an accident, so those few extra inches won’t be a danger. However, drivers who already sit closer to the steering wheel may be at greater risk of colliding with the steering wheel if their seatbelt extends those extra inches.

While many modern cars have this setup, it’s not the case for all vehicles. My 2021 Subaru Outback has these fabric safety loops on every main seat belt. Other models, like some years of the Toyota Prius, have no loops on any of the belts—this isn’t necessarily a problem; it’s just the way the automaker designed the cabin.

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What does the button on a seat belt do?

There is a small, plastic button on car seat belts that you may notice. This is not a safety feature; rather, it’s a simple convenience feature. The button, called a seat belt stop, works by preventing the buckle from sliding too far down the belt. If you’ve ever driven in a car without a stopper, you’ve probably experienced the frustration of having to fish around for the buckle.

The seat belt stop is just for convenience. If some reason, you didn’t want it there, you can remove it easily and not compromise the safety of the belt.

Do seat belt covers affect the safety loop?

You may be concerned about compromising the effectiveness of seat belts by adding a seat belt cover, but it’s unlikely that a simple cover would be able to affect the energy management loop. In the event of a collision, the loop would very likely still perform its intended function and rip open. It’s also very likely that, even if a cover could somehow get in the way, it would also tear under pressure.

Keep this safety feature in mind for seat belt replacement

A hand holding the buckle and energy management loop portion of a Subaru Outback's seat belt
Energy management loop | Becca Hopkins, MotorBiscuit

Unless you find yourself needing new automatic seat belts for your older car, replacing a seat belt is a relatively easy thing to do. Whether you salvage some good-condition belts from a local junkyard or buy them directly from a manufacturer, keep this information in mind. 

You may want to look for seat belts with a safety loop specifically, or you may want to avoid this fabric feature for the driver’s side if you’re concerned about risk.

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