Are Car Seats with Seat Belts and Lower Anchors Safe?

2 YEAR OLD BOY IN CAR SEAT
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Children's car seats can be installed with a seat belt or the lower anchors of the LATCH system. LATCH stands for Lower Anchors and Tethers for Children. Parents—especially when the car seat isn't getting tight—often make the mistake of using both the lower anchors and the seat belt at the same time.

However, unless your child's car seat is one of the few that specifically states to use both seat belt and lower anchors at the same time, you'll need to choose one or the other, not both.

Forward-facing car seats all come with a tether strap, which secures the top of the car seat to an anchor in the back of the car. Every forward-facing car seat is safer (and better able to protect your child's brain and spinal cord) when you use the tether strap. Regardless of whether the forward-facing car seat is installed with the seat belt or the lower anchors, you always add the tether strap in addition.

The LATCH System: Lower Anchors and Tethers

The lower anchors are metal U-shaped or horizontal bars that can sometimes be hidden inside your vehicle's seat crease (or be visible sticking out from the crease). In most cars, you'll find two sets of lower anchors—one on the driver side and the other on the passenger side—in the back seat. A few vehicles may have lower anchors in the center of the back seat.

The tether anchor is the second part of the LATCH system in your vehicle. It can look like the lower anchors, but there's only one per set of two lower anchors. The tether may be on the back of the vehicle seat, in the ceiling (SUVs and station wagons), or on a shelf behind the seat (sedans).

The Car Seat Lady has information on where you can find the lower anchors and tether anchors in any American vehicle made from 2000 to 2020.

Why You Can't Use the Seat Belt and Lower Anchors Together

Car seats are designed to handle crash forces in specific ways. Thanks to federally mandated crash testing, we know that a car seat will withstand the forces of a 30mph frontal crash when installed with the seat belt OR with the lower anchors of the LATCH system. However, we do not know if the same car seat will perform properly when the seat belt AND the lower anchors are used at the same time.

There are several reasons that installing a car seat using both the lower anchors and the seat belt at the same time may be unsafe. Putting two installation belts through the same belt path could increase the crash forces applied to a particular area of the car seat, possibly causing the car seat to break or perform in ways that cannot easily be predicted. Additionally, using two installation belts could put additional force on the car seat, possibly causing it to perform in ways that cannot be easily predicted.

Always install and use the car seat exactly as the manufacturer specifies in the instruction manual.

If you install the car seat using methods that are not outlined in the seat's instruction manual, it's like you're using your child as a crash test dummy. You can't be sure of what will happen when car seats are used in ways that have not been crash-tested and approved. To find out how your car seat should be installed, check the car seat instructions as well as your vehicle's owner's manual.

If you cannot get the car seat installed tightly using either the vehicle seat belt or the components of the LATCH system, find a certified child passenger safety technician or a car seat inspection station by visiting Safe Kids USA.

Which Installation Method Is Best?

Every position in the car has a seat belt, but not every position (usually) has the lower anchors. If the car seat is going to be installed in the center seat, for example, this will almost always require using the seat belt. If the car seat will be installed on one of the side seats, you'll often have the choice between the lower anchors or the seat belt.

You should choose the installation method that allows you to get the best fit for your vehicle. A car seat is installed correctly when you cannot move it more than an inch in any direction when you grab the car seat at the belt path. After verifying that the seat is tight, make sure it is angled properly—reclined for rear-facing kids and more upright for forward-facing kids.

Remember that even though you have to pick between the vehicle seat belt or the lower anchors (part of the LATCH system), the tethers are used in addition to the vehicle seat belt or lower anchors for every forward-facing installation.

You also need to keep in mind that the lower anchors of the LATCH system have a weight limit. You will need to switch to a seat belt installation once your child reaches the weight limit and the lower anchors can no longer be used. The lower anchor weight limit is listed on the car seat labels and in the instruction manual.

Currently, there are several seats that do allow the use of the lower anchors and seat belt simultaneously. Carefully review the information on the product you've purchased to ensure you understand how to install it safely.

As of 2020, all of the car seats that allow lower anchors and seat belts at the same time feature rigid LATCH rather than a lower anchor (LATCH) strap.

However, it's important to keep in mind that car seat safety information can change quickly as manufacturers put out new seats.

Always read that instruction manual—even if you think you're already very familiar with the car seat model. Some of the updates might apply to newer versions of the same car seat.

What About Booster Seats?

The lower anchor weight limits only apply to car seats (where the child is restrained by a 5-point harness). Lower anchor weight limits do not apply to boosters (boosters are seats where the child sits on the booster and uses the vehicle's seat belt across them as the restraint).

Many booster seats can connect to the vehicle's lower anchors. It is safe for the booster to be secured to the lower anchors while the child is secured using the vehicle's seat belt across them.

Boosters are positioning devices and do not take much (if any) of the forces in a crash. Car seats, however, are the restraint for the child and take a great deal of force in a crash, and in so doing put tremendous force on the parts securing them to the vehicle (lower anchors or seat belt). Seat belts are designed to withstand much more force than the lower anchors.

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Article Sources
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  1. Williams JR, O'Donel CA, Leiss PJ. Effects of LATCH versus available seatbelt installation of rear facing child restraint systems on head injury criteria for 6 month old infants in rear end collisions. Traffic Inj Prev. 2015;16 Suppl 2:S16-23. doi:10.1080/15389588.2015.1067804

  2. Lynberg M. Car seats and booster seats. National Highway Traffic Safety Administration. Published September 10, 2019.

  3. Greenbauer L. How to install an all-in-one car seat rear-facing. National Highway Traffic Safety Administration. Published October 3, 2017.

  4. The Car Seat Lady. LATCH weight limits. Updated 2020.