3-Across Carseats: Making the Impossible Possible!

Best Narrow Car Seats & Tips for Installing Three Car Seats in One Row

Three-across is one of the most challenging tests of any parent or child passenger safety technician’s abilities. Correctly installing three car seats in one row can often be a big challenge, and telling a family to get a larger vehicle isn’t usually an option. Even buying three new seats can cost a lot, but it’s definitely a lot less expensive than a new vehicle. Fortunately, manufacturers are now offering narrower products to make this challenge a bit easier, and knowing some tips and techniques can help a lot, too.

As a mother of four, and a certified Child Passenger Safety Technician-Instructor who works closely with families of multiples (twins, triplets, etc.), I have a lot of hands-on experience with fitting three (or more!) seats in a variety of vehicles. Here are some tips to help you safely accommodate multiple children.

Before we get into the tips, remember: Car seats can touch, but they must each be independently tight – not just appearing to be snug because they’re smashed up against each other. If you remove one seat, the adjacent seat still needs to be properly installed. Remember to read your car seat and vehicle manuals, and always follow the manufacturer’s instructions.

For more info on car seat touching and “puzzling” see our article: Mythbusting: 3-Across & Adjacent Car Seat Installations

Tip #1. Consider Tether Anchor and Head Restraint Locations

While car seats can be installed in any location with a seatbelt, it’s strongly recommended that all forward-facing child restraints be installed in a seating position with a top tether anchor. (It is also legally required for all seats in Canada and with a few child restraints in the United States.) Since vehicles are only required to have a total of three tether anchors, this means that some three-row vehicles do not have a tether anchor in each seating position. Start by identifying which seating positions in your vehicle have tether anchors and try to place your forward-facing child restraints in those positions.

Another potential issue is that some seating positions, particularly those in the middle, might not have head restraints. It’s important to understand whether your child restraint requires head support behind it, so check your manual. All passengers need head support up to at least the top of their ears, so any backless booster riders (or older children/adults in just seatbelts) need a seating position with adequate head support.

At first glance, this setup looks great: Three narrow boosters with room to spare! But . . . this likely won’t work due to the lack of a head restraint in the center.

Graco GO, BubbleBum, Graco RightGuide

Tip #2. Seatbelt vs. Lower LATCH Anchors

While lower LATCH anchors (where available) often provide an easier method of installation, in a 3-across situation it may benefit you to install your car seats with the seatbelt instead, even if the child is still under the LATCH weight limit. The benefit of using a seatbelt is that it offers more flexibility on the exact placement of your car seats. Lower anchors are in a fixed location and only 11” wide, so they will force your car seat to go exactly where the lower anchors are located. When we install with a seatbelt, we can often gain precious space by installing the car seat a little closer to the door of the vehicle, for example. Just be sure the base of the child restraint is completely on the vehicle seat and not hanging over the side. In all of our examples, we used the seatbelt instead of the lower LATCH anchors. If you happen to have a vehicle with inflatable seatbelts, be sure your child restraint is compatible with them. Otherwise, you’ll need to use lower anchors (if the child isn’t too heavy) or will need to use a different seating position for that child restraint.

Overlapping seatbelts aren’t inherently a problem, but it’s important to make sure they don’t interfere with a tight installation. If you do find that overlapping seatbelts interfere with a good installation, you might need to consider using LATCH for one of the seats instead. Also, sometimes different combinations of seats will work next to each other when others won’t, due to their shape or the way the path for the seatbelt is located. For example, a seat with a low belt path next to one with a high belt path can help avoid interference.

Tip #3. Lockoffs/Belt Tensioning Systems

Since seatbelt installations often give us the most flexibility with three-across arrangements, a lockoff and/or a belt tensioning device can be a very valuable feature. A lockoff can allow us to position the car seat a bit more towards one side or another depending on what is needed for the arrangement. Powerful belt tensioning devices like Britax ClickTight, Graco SnugLock, and Nuna TrueTension can be helpful even if the seat isn’t particularly narrow. Seats with belt tensioning devices may or may not require you to lock the seatbelt so be sure to read your manual!

See how close to the edge of the seat we were able to install this? This gave us precious space in the center for the other convertible seat to fit.

Boulevard CT

Tip #4. Try Multiple Arrangements

If one arrangement of three seats doesn’t work, try them in a different order. Look closely at the contours of your vehicle seats. For example, midsize SUVs sometimes have a passenger side seating position that is wider than the driver’s side, or vice-versa. Try putting a different child restraint there and see if that helps your set-up.

This is the 2020 GMC Terrain. You can see that the seat on the passenger side is slightly wider than the driver’s side. This means that a narrow backless booster might work better on the driver’s side, with a larger convertible seat on the passenger side and in the center. Unfortunately, this arrangement could make it difficult if you need to drop an older child off at school/activities where they must exit the vehicle on the passenger side, so be sure to consider real-life situations when deciding on the “best” scenario.

2020 GMC Terrain

Graco RightGuide, Nuna Rava, Boulevard CT

Tip #5. Don’t Forget to Attach the Infant Seat!

At first glance, it may seem like it’ll be no problem to get all of your seats installed. The base for the infant seat might fit just fine next to big brother’s seat, but wait! Did you try attaching the carrier portion of the infant seat to the base? The carrier is significantly wider than the base, so be sure it attaches without interfering with the adjacent seats. Remember when I said that seats touching each other are OK? Be extra careful if the infant seat is touching something else because it might be keeping the infant seat from attaching securely to the base. Depending on your situation, this may be a reason to go straight to a convertible that fits smaller babies to avoid any chance of the infant seat not fully securing!

Tip #6. Booster or Harness . . . Choose Wisely!

Many people assume that moving a child into a booster seat will help in a three-across situation. However, booster seats aren’t necessarily more narrow than harnessed seats, and even when they are, young children need extra room next to them in order to reach the seatbelt buckle. If you have tight space in the back seat, it might be better to keep a booster-ready child in a harness as long as they still fit. Once the child needs to move to a booster seat, look for lower-profile ones that might offer more space for a child’s hand to reach in to buckle up. (Try them out if you can!)

On the same theme, it might also make sense to keep a child rear-facing longer to allow more room for adjacent forward-facing seats, particularly for booster riders. Consider ALL of your options!

You’ve tried all of the tricks above and nothing works. Now what?

Tip #7. Test Out New Seats

If you’ve tried the seats you have in a variety of different arrangements and using different installation methods but they still don’t work, you’ll need to consider either new car seats or a new vehicle. Most people choose to explore new car seats first! If you have a store near you that allows you to try seats in your vehicle before you buy, that’s ideal. If you don’t have a store that will let you do that, ask around to see if anyone you know has other types of car seats you can try before you order them.

When you’re trying out seats, don’t just set the seats in the vehicle. You have to actually install them to determine if they will work safely or not. You might consider hiring a CPST to go with you during this exercise to ensure the combination you’re buying will actually work. Technicians can often teach you some tricks to maximize the space you’re working with and can advise which seats might be best to try. If you do choose to shop for a new vehicle, bring your car seats with you. When my family purchased our last vehicle (awaiting the arrival of our 4th child) I brought six different seats with me to 4 dealerships! With a 6’7” husband and four kids, I knew I needed to make sure everything was going to work before we made such a big commitment.

Best Narrow Car Seats for 3-Across

If you find yourself in need of new seats, here are a few of my go-to seats for maximizing space in your vehicle. I’ve also noted a few pros/cons specifically related to installing three-across. Be sure to read full reviews and the manual to understand all aspects of the child restraint. And as mentioned above, try them out first when possible!

Best Narrow Rear-Facing-Only Car Seats for 3-Across

Graco SnugRide SnugLock: While there isn’t a significant difference in the width of most infant car seats, a powerful tensioning lockoff like SnugLock can really assist with 3-across arrangements by allowing you to position it closer to the door. The regular Snuglock base with the lever is narrower than the DLX SnugLock base with the larger swing arm.

Chicco Keyfit 30: A go-to seat for compatibility in many vehicle seating positions due to its slightly smaller external dimensions and handy lockoff.

Clek Liing: Slightly narrower than average with a tensioning lockoff plus a load leg. Liing’s rigid LATCH attachments are an awesome feature but you might need to forgo them in favor a seatbelt installation that can offer more flexibility on the exact placement of the base.

Best Narrow Convertible & 3-in-1 Car Seats for 3-Across

Graco SlimFit3 LX: The first car seat designed specifically for 3-across situations! It’s also a tall seat, typical of a Graco 3-in-1 product, so kids will make it to the full 40 lbs. rear-facing. But most of all, it’s skinny at the right price. The bang for the buck is there: Rear-facing, Forward-facing, highback booster in a car seat that’s only 16.5” wide. That’s hard to beat! See our complete review of the Graco SlimFit3 LX here.

Britax Marathon/Boulevard ClickTight: While these two convertible seats aren’t the narrowest, they are more narrow than most on the market, and more importantly, their powerful lockoffs can be very valuable in tight situations. (Notice we left off the Advocate because it’s just too wide for most 3-across situations.) See the photo above in tip #3! See our review of the Marathon CT here and the Boulevard CT here.

Clek Fllo/Foonf: Clek seats are among the narrowest on the market. They don’t offer many options for recline adjustment, so you’ll want to make sure they fit behind the front seat. Believe it or not, sometimes the Foonf, even though it’s large, fits well rear-facing because it sits high enough to clear the front seat’s headrest. See our review of the Fllo here and the Foonf here.

Cosco Scenera NEXT: The Scenera NEXT is another compact, budget-friendly convertible seat that offers quite a bit of longevity for the price. It actually lasts longer rear-facing than it does forward-facing, so keep that in mind if you choose this seat. See our Scenera Next review here.

Diono Radian: The Radian 3R, 3RX & 3RXT convertible seats are known for their narrow profile. Be sure to read the manual carefully, though, because they can be tricky to install correctly. They also tend to take up a LOT of front-to-back space when installed rear-facing, so be sure they fit behind the seats in front of them. A separate “Diono Angle Adjuster” can be purchased to make the rear-facing Radian more upright for older babies and toddlers who can sit up unassisted and have complete head control. For a helpful tip installing your Diono convertible seat forward-facing, check out this video:

Best Narrow Forward-Facing Combination Seats for 3-Across

Chicco MyFit: If you’re looking for a full-featured combination seat, the MyFit is a great option. The cup holders fold in to gain precious space. Besides being narrow, the MyFit also has lockoffs. The buttery smooth harness adjustment is also fantastic if you have this seat in the middle and need to turn around to tighten a child’s harness! See our review here.

Cosco Finale: The Finale is a very budget-friendly combination seat; however, it does require the use of the tether, so make sure you put it in a seating position that has a tether anchor. (We always recommend using the tether but it’s not optional with this seat.) See our review here.

Best Narrow High Back Boosters for 3-Across

Peg Perego Viaggio FlexThis narrow highback booster is pricey but it has no armrests so it fits well next to other seats and it’s easy for kids to buckle themselves.

Best Narrow Backless Boosters for 3-Across

Bubblebum: This inflatable booster seat offers a very narrow and flexible booster option for big kids, but thigh support is limited. See our review here.

Cosco Rise: The Rise is a traditional booster with a narrow profile and a very modest price point. However, in very tight 3-across arrangements the armrests can make it challenging to buckle the seatbelt.

Other Restraint Options for 3-Across

Ride Safer Travel Vest: The vest is a cross between a 5-point harness and a belt-positioning booster seat and only takes up the width of the child, making it a wonderful solution for 3-across. Another benefit of this product is that the child sits directly on the vehicle seat, which may eliminate the issue of head restraints. This can be a lifesaver when you’re trying to overcome challenges with smaller vehicles or a lack of vehicle head restraints.

Three-Across Pics to Inspire You . . .

We obviously can’t try every single combination. Even this basic amateur photo shoot took 2 hours with two technicians . . . and a Yukon XL-load of seats! But hopefully, through these photos, we can point out a few things to assist with your situation.

Look at how nicely that vest fits between those two traditional restraints AND how there’s no issue with the lack of head restraint in this particular center seating position! We could actually accommodate a fairly tall child in this seat thanks to the Ride Safer Travel Vest. The Evenflo Spectrum also makes it fairly easy to reach the buckles with the open belt path. (This photo below was taken in the 3rd row of a 2016 GMC Yukon XL.)

Evenflo Spectrum, Ride Safer Travel Vest

The belt tensioning devices on these two seats (Britax Boulevard ClickTight and Nuna Rava, below) make it very easy to get solid installations and the open design of the RightGuide means we can get these three seats in the small GMC Terrain. However, notice the booster rider is on the driver’s side . . . while this gave our booster rider a bit more space, it’s not going to work very well if they have to climb out for school drop-off, etc.

Graco RightGuide, Nuna Rava, Britax Boulevard CT

This would be a great setup for say, a young elementary school child (Chicco MyFit, below) on the passenger side for easy drop-off/pick-up with the baby and toddler rear-facing in the center and driver’s side. The powerful lockoff/belt tensioning system on the Britax Boulevard ClickTight made it relatively easy to get these three seats installed in the GMC Terrain. And the little Combi Coccoro is a great seat if you need something narrow for the middle seating position.

Boulevard CT, Combi Coccoro, MyFit

The Ride Safer Travel Vest (center) fits just about anywhere! Don’t forget to check for proper head support if you are using the vest. Since this seating position lacks an adjustable head restraint, the child will need to be short enough that the top of the ears are no higher than the vehicle seat back.

Maxi Cosi RodiFix, Ride Safer

AutoNation Buick GMC of Park Meadows let us use their beautiful 2020 GMC Terrain and GMC Acadia for our photo shoot. The Terrain has a second-row hip room measurement of 51.8″ while the Acadia measures 53.3″. We didn’t really “feel” the extra space in the Acadia, which just goes to remind you that you can’t simply go by the hip room stats. Always try it out when possible!

2020 GMC Acadia

2020 GMC Acadia

2020 GMC Terrain

2020 GMC Terrain

Notice how narrow the middle seats are below? Realistically you probably won’t find any traditional seat that will fit in the center and allow the passenger side to tumble for third-row access, except maybe the base of a few infant seats (without the carrier attached). The Ride Safer Travel Vest will easily allow you to tumble the passenger seat but you may need to consider how you’ll use and access the 3rd row if necessary.

2020 GMC Acadia

2020 GMC Acadia

2020 GMC Terrain

2020 GMC Terrain

Editors’ Note: There is NO substitute for experience. Some three-across guides online are compiled from internet sources and the authors have zero first-hand knowledge of the products they recommend. There are ALWAYS unusual issues and exceptions, so you MUST read your vehicle and car seat manuals. Consult with a local, certified child passenger safety technician if you are unsure if your seats work in adjacent or 3-across setups!

Thank you to AutoNation Buick GMC Park Meadows for their support.



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