One of the most challenging and also satisfying parts of being The Car Seat Lady is figuring out which car seats will work best in tight side-by-side or 3-across situations. We’ve created a guide to help you narrow down (pun intended!) the options when you have to fit a bunch of car seats together in a small space.
We’re going to first explain why we’ve chosen the seats on this list and how vehicle geometry and car seat design interplay in this situation. Scroll down if you want to go straight to the list.
Because of our experience! We’ve actually installed these car seats in hundreds of vehicles in thousands of combinations! So we know what’s most likely to work and what likely won’t work. We’ve included the infant seats that, based on our experience, are the most likely to work in the greatest number of combinations.
To make the list, a narrow car seat must also meet some other criteria:
Size and Shape: Size doesn’t matter (too much). Put away your measuring tape! What matters more for the car seat is how two or three car seats work together, and for the vehicle is how much usable space there is in the back seat.
For the car seat: When we choose a car seat for a three across set-up we look at the car seat’s total design, not just the width. Car seats aren’t rectangular boxes. They’re 3D objects with curves. Some sit up higher on the vehicle seat, others sit lower. Fitting 2 seats side by side is a 3D puzzle: where one car seat flares out another may be narrowest and they can puzzle together nicely. Likewise, a seat that sits low to the vehicle seat may tuck nicely next to a seat that sits high off the vehicle seat.
For the vehicle: This logic applies to the car too! The total width of the back seat doesn’t actually matter (too much). In most vehicles, there are many inches of wasted space between the door and where the seat belt is anchored. This is room that car seats can’t occupy when tightly installed. Total hip room also doesn’t matter, because very frequently the backseat is not divided up with an equal amount of space for each passenger.
Installation with the seat belt is often required for a three across set up. Why is this required if there are lower anchors in the vehicle? Lower anchors are usually centered on a vehicle seat, and as such they restrict the placement of the car seat to right in front of where the anchors are placed. When we need to put three car seats across, we usually need to use ALL the available usable space on the vehicle seat to give the center car seat enough space, which means having the car seats near the doors be slightly closer to the doors then they’d be if they were centered on the vehicle seat when installed with LATCH. If you’ve read this page regarding LATCH in the center or this page regarding locating lower anchors in your vehicle, you already know that you typically can’t use LATCH to install a car seat in the center position….which means all three car seats must be installed with the seat belt.
Because installation with the seat belt can be difficult, we favor car seats with built-in seat belt locking devices. These lock-offs usually make installation MUCH easier, which we hope leads to less misuse. These lockoffs can also make it possible to get the car seat secured in close-to-the-door positions where using the seat belt’s own locking mechanism would not provide a tight installation.
High enough height and weight limits: Some narrow seats have a very short usage due to low shell height or top shoulder strap slot. We left those off our list! Figuring out this three across or two together situation is hard enough to do once–we don’t want you to have to do it again in 6 months when your child needs a bigger seat!
We’ve selected three infant seats that we’ve found to work in a wide variety of tight situations.
Easy and flexible installation with the seat belt: A great seat belt tensioning and locking device on the Liing’s base allows for a secure installation when positioned closer to the door than with many other seats (other seats would be loose if positioned that close to the door).
Unmistakably tight Rigid LATCH installation means you KNOW the seat is tight. If it fits, this can be super useful in a tight side-by-side or 3-across situation, because in these situations it can be harder to tell if the car seat is truly installed tightly or just feels tight because its wedged next to another car seat.
Visual indication that carrier is locked into base. We love this feature because it’s very helpful in a side-by-side or 3-across setup where the car seats are packed so closely together that you may not be sure that the carrier snapped in all the way.
Fits behind tall drivers. The Liing takes up less space from front-to-back compared to other infant seats, so it tends to fit better behind taller drivers or passengers. This means its more flexible in where you can install it in the vehicle–you are not limited to a behind-the-passenger position (for this reason anyway).
Easy and flexible installation with the seat belt: Thanks to the Fit2’s anti-rebound bar and built-in seat belt locking device, it often tolerates a seat belt installation positioned closer to door than do other seats. We use this car seat a lot in tight 3-across situations.
Easy LATCH installation: Smoothly pulling LATCH adjustment strap is easy to make tight.
Longevity: The Fit2 likely lasts longer than any other infant seat due to its adjustable head rest, which moves up quite high. Having a long-lasting infant seat is key to keeping your 3-across setup for as long as possible. Once the baby moves out of the infant seat, you must figure out a new 3-across combo, and who wants to do that?
Fits behind tall drivers. The Fit2 takes up less space from front-to-back compared to other infant seats, so it tends to fit better behind taller drivers or passengers. This means its more flexible in where you can install it in the vehicle–you are not limited to a behind-the-passenger position (for this reason anyway).
Center seat compatibility: The Fit2 often fits particularly well in center seats in between two forward-facing seats or boosters
Note: The Chicco Keyfit30, while very similar in appearance to the Fit2, is a completely different car seat that does not work similarly in these tight situations and is therefore not on our list.
Easy and flexible installation with the seat belt: Thanks to the Snugride’s Snuglock belt tensioning and locking device, this base often tolerates a seat belt installation positioned closer to the door than other car seats.
Easy LATCH installation: Smoothly pulling LATCH adjustment strap is easy to make tight.
Longevity: One of the longest lasting infant car seats. Having a long-lasting infant seat is key to keeping your 3-across setup for as long as possible. Once the baby moves out of their infant seat, you must figure out a new 3-across combo, and who wants to do that?
Fits behind tall drivers. The Snugride Snuglock 35 DLX/Elite/Platinum takes up less space from front-to-back compared to other infant seats, so it tends to fit better behind taller drivers or passengers. This means it’s more flexible in where you can install it in the vehicle–you’re not limited to a behind-the-passenger position (for this reason anyway).
Convertibles with high height and weight limits, enabling rear-facing for as long as possible
Perfect if you need to fit 2 car seats next to each other or 3 car seats across one row, or if you just have a small vehicle.
If you need to fit 2 car seats next to each other, or 3 car seats across one row, these boosters are the seats for you.
The best booster seats for your bigger-than-average kiddo, with safety, comfort, and longevity in mind.
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FTC Disclosure: Affiliate links are included in this page. No monetary compensation was provided, however, a few of the reviewed products were supplied by the manufacturer or distributor to help facilitate the review. All opinions are those of The Car Seat Lady, LLC.