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.
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 and roominess: Some narrow seats have a very short usage due to low shell height or top shoulder strap slot. We left those off our list! All of our recommended seats are roomy on the inside even if they’re narrow on the outside. In fact, we’ve taken care to choose seats in each category that are at least as comfy, if not more roomy, than the other seats in their category that happen to be wider on the outside. Figuring out this three across 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 convertible seats that we’ve found to work in a wide variety of tight situations.
Super narrow footprint and width: The Graco Slimfit3 LX is probably the narrowest seat out there right now! Cupholders are removable to make the seat even more narrow.
Easy rear-facing LATCH installation: Fits well on the side installed with lower anchors. Lacks a seat belt lockoff for rear-facing so not ideal for a rear-facing center installation or side installation with the seat belt, which does mean it may sit more centered than is desired in a tight 3-across situation. Still worth a serious try though due to its narrow width.
Fits in very tight side spaces due to seat belt installation: With built in seat belt lockoffs, a rear-facing Foonf can be placed slightly over towards the door to accommodate another car seat or passenger next to it. A seat belt installation also means there’s no need to worry about LATCH weight limits when used rear-facing.
Extremely narrow on the outside but still super comfy: This seat is narrow and streamlined on the outside but very roomy and comfy on the inside, even for bigger kids.
Fits well behind the driver or passenger: The Foonf can sit fairly upright so it’s a great choice for placement behind even a taller driver or passenger. (Older kids often prefer to sit more upright in the car) Note: Because it sits quite high off the vehicle seat, the Foonf can cause an obstructed view out the rear window when installed in the center of many vehicles, especially as a child grows and the headrest moves up.
Longevity: The Foonf can be used rear-facing until a child is 44 inches or 50 lbs. This means even a 95th percentile boy can use this seat rear-facing until his 4th birthday. The mandatory anti-rebound bar means your child will have lots of legroom.
Can be used for a newborn: The Infant Thingy, sold separately, makes the Foonf suitable for newborns. This is particularly helpful for vehicles that don’t have enough room to fit an infant seat in a 3-across set up.
Fits well in the center seat due to seat belt installation: Because it comes with built-in seat belt lockoffs, the Fllo fits very nicely in the center seat, where a LATCH installation is not usually possible. The built in lockoffs mean the seat can be placed slightly off-center to accommodate another car seat or passenger next to it. A seat belt installation also means there’s no need to worry about LATCH weight limits when used rear-facing.
Extremely narrow on the outside but still super comfy: The Fllo is narrow and streamlined on the outside but very roomy and comfy on the inside, even for bigger kids. Great for installation next to other car seats and when used in the center, usually allows both front seats to come all the way back.
Longevity: The Fllo can be used rear-facing until a child is 44 inches or 50 lbs. This means even a 95th percentile boy can use this seat rear-facing until his 4th birthday. The anti-rebound bar is optional, but when used will give your child a lot of legroom.
Can be used for a newborn: The Infant Thingy, sold separately, makes the Fllo suitable for newborns. This is particularly helpful for vehicles that don’t have enough room to fit an infant seat in a 3-across set up.
We’ve selected five forward-facing 5-point harness car seats that we’ve found to work in a wide variety of tight situations.
Super narrow footprint and width: Probably the narrowest seat out there right now! Cupholders are removable to make the seat even more narrow.
Choice of installation with either LATCH or seat belt: Graco’s Slimfit3 LX Works nicely forward-facing with LATCH until child is 45 lbs, or with the seat belt and tether until 65lbs. Built in seat belt lockoff means seat does not need to be centered between lower anchors. Using the seat belt, it can often be secured slightly towards the door/off center, enabling 3 across. Remember to always use the tether when forward-facing.
Note: When purchasing, make sure you are getting this seat, the Slimfit3LX, and not the similarly named Slimfit 3-in-1, which is a completely different seat that is not very slim despite it’s misleading name. Be very careful, the two seats are often listed on the same Amazon product page! The Slimfit3LX has a gray lever on its headrest and a small black base that is more narrow than the actual seat, with a grey lever to adjust the seat’s recline angle. The Slimfit 3-in-1 has a red lever on its headrest and a wide base with a red lever to adjust the recline angle.
Assured super tight installation, even in a 3-across situation (as long as the Foonf can be installed, it will be tight): Because the forward-facing Foonf uses Rigid LATCH and therefore plugs into the vehicle’s lower anchors, you’ll never need to worry that it’s installed too loosely. This is important in a 3-across situation where you must be certain that all three seats are independently tight, and they don’t just seem tight because they’re smack up against each other. The Foonf is the only forward-facing 5 point harness seat sold in the US to feature Rigid LATCH at this time.
Extremely narrow on the outside by still very comfy: The Foonf is narrow and streamlined on the outside but very roomy and comfy on the inside, even for bigger kids.
Longevity: Can be used forward-facing until about age 6.
Note: Great option for the side seats, NOT the center: Because the Foonf uses Rigid LATCH, it’s best placed on the side seats. It often fits nicely next to a rear-facing Clek Fllo in the middle seat. The Foonf is not a good choice for a forward-facing seat in the center because most vehicles do not have lower anchors in that position.
Other things we like, besides the narrow parts:
Extremely low profile, narrow width, and shallow sides make it a great option for tight center spots: The Radian’s design means it tucks in nicely next to other car seats, especially rear-facing seats. Often works well in the center with two rear-facing Foonfs on either side.
Easy to maneuver around and in/out: Kids have an easy time climbing in and out due to the Radian’s shape. It’s easier to get an infant carrier out of the center if the Radian is on the side (compared to a higher forward-facing seat.) Finally, it sits low to the vehicle seat so it’s less likely to obstruct a driver’s view out the rear window when its installed in the center.
Longevity: Most kids will fit until about age 6.
Note: Installation can often be tricky! In many vehicles you’ll need to use a locking clip and/or the double seat back recline trick. Also requires changes to straps, crotch buckle, and base over time which means reinstalling several times, and this can be annoying especially if installation is difficult.
Note: Not recommended for rear-facing: The Radian does not meet our criteria for a recommended narrow rear-facing convertible car seat because its rear-facing seat belt installation often does not yield a tight result and because when installed with LATCH, doesn’t accommodate another car seat next to it.
Easy LATCH installation can be completed in under 3 minutes.
Easy to maneuver around and in/out: Kids have an easy time climbing in and out due to the Go’s shape, especially when the Go’s in the center. It’s easier to get an infant carrier out of the center if the Go is on the side (compared to a higher forward-facing seat.) The Go sits low to the vehicle seat so it’s less likely to obstruct a driver’s view out the rear window when its installed in the center. Finally, its lack of sides means an adult will be more comfortable sitting next to the Go than most other forward facing seats.
Longevity: Fits most kids until about age 6.
Extremely narrow on the outside but still super comfy: The Go is narrow on the outside but very roomy and comfy on the inside, especially for kids who like to sit criss-cross.
A forward-facing option for the center: Because its narrow and lacks sides, the Go works well installed with LATCH in the center (as long as the vehicle permits this) next to two rear-facing seats on the sides. Note that the seats next to it will likely need to be installed with the seat belt. Using the Go in the center may permit a family to install their infant seat on the side (instead of in the center, which is less convenient.)
Allows third row access in specific vehicles, when other car seats don’t: Great on vehicle seats that first fold forward and then slide forward for third row access. The IMMI Go can usually stay securely installed while the vehicle seat folds forward, unlike other forward-facing car seats.
Other things we like besides the narrow parts:
Note regarding installation: The Go does not want to be installed with the seat belt. It absolutely needs to be installed with the lower anchors and tether strap.
Great seat belt installation, especially on side seats: Nicely designed seat belt lockoff holds the seat belt tight and allows for an installation close to the door.
Longevity: Very high height capacity means this seat will last longer than others. Almost all children will fit in harness mode until about age 7. This is helpful in a tight three across situation where a booster would be hard to operate (because it is often very hard to buckle and unbuckle the booster’s seat belt in a tight 3-across. Using a harness instead of the booster removes this difficulty).
Other things we like (besides the narrow parts):
Note: We don’t recommend the Myfit in booster mode because the arm rests make buckling a challenge and because the shoulder belt tends to get stuck in the shoulder belt guide when a child leans forward. This is problematic because the seat belt is then too loose on the child.
Great seat belt installation in center or side seats: Fantastic seat belt tensioning device allows for an easier, tighter installation in most seating positions.
Accommodates protruding vehicle head restraints and rigid, angled seat belt buckles: The Exec’s design means it fits nicely even when vehicle features present a challenge. It’s very hard to find forward-facing seats that work with these vehicle features.
Longevity: Fits most kids in forward-facing mode until age 6. Note that booster mode is short-lived; your child will likely need another booster with higher height limits before they can pass the 5-Step Test to use the vehicle seat belt on its own.
Good visibility for the child using it: Because the Exec sits high off the vehicle seat, a child can easily see out the window. This is great until the child gets tall, when it can start to become a visibility issue for the driver if installed in the center position.
Other things we like (besides the narrow parts):
Diono Radian for Rear-Facing: Often won’t install securely with the seat belt, and has short usability (only 35 lbs) when installed rear-facing with LATCH.
Graco SlimFit: Lacks built-in seat belt locking device and not very slim.
Cosco Scenera NEXT: Lacks built-in seat belt locking device and won’t typically install securely when positioned close to the door. Also has limited capacity due to its small size.
Combi Coccoro: Typically difficult to install tightly. Also has limited capacity due to its small size.
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.