How Do You Fit Three Car Seats Across? | Ask A CPST
Help! I need to fit three car seats next to each other! Where do I begin?
Hi, I’m Sam! Like Kelly the Car Mom, I’m a Child Passenger Safety Tech (CPST) and a mom of three. Kelly and I are here to familiarize you with car seat safety, car seat use, and car seat selection so that you can make the decisions that feel right (and safe) for your family.
So… you need three car seats?
You’ve heard of the three-kids-under-three club, but an equally as daunting club can be the three-across club. Maybe your second child became, surprise!, your second and third children. Or maybe you’re ready to expand your family, but not your car payment. Or perhaps you just like the trunk space a three-row SUV can provide with the third row down.
Well buckle up, because we’re going to simplify this game of tetris and help you set yourself up for three-across success!
Before purchasing three car seats, here’s what you need to know
The hard facts first, not every vehicle is three-across compatible. Some vehicles can fit three rear facing car seats while others can only fit a combination of rear-facing, forward-facing and booster seats. This can change down to a model year and trim due to something like severe seat belt overlap. More on that later, but just be aware that while one person could fit three car seats in their car doesn’t necessarily mean your combination of seats will work. To see my favorite vehicles for three across, check out my complete guide here.
An important note before we dive into the details: be sure to consult your car seat and your vehicle manual. Searching out a local CPST may also prove to be an invaluable resource in your three-across set-up.
To safely fit three car seats next to each other, a handful of things must be possible and I’ll outline them below. This guidance is summarized from the Harmonized Statement made by the Manufacturer’s Alliance for Child Passenger Safety (MACPS.) MACPS is made up of representatives from the child restraint and vehicle manufacturer industries to help support CPSTs and child passenger safety education as a whole.
Three Across Guidance:
The car seat is independently secure, meaning it moves less than one inch in all directions
Everything is correctly aligned. The position of the car seat on the vehicle seat is still correctly aligned with the seat belt or lower anchors. (Another car seat isn’t pushing it out of alignment.)
The car seat is not overlapping the seat next to it. The seats can touch each other and puzzle into each other’s “air space,” but the seats can’t be deformed to where they’re occupying each other’s space. This creates the illusion of a tight installation.
No contact or force that would bend or deform any of the car seats.
Lower anchor points must all be aligned. Seats can be adjustable front-to-back, but staggering cannot occur due to safety concerns.
Only one lower connector is connected to one lower anchor point - unless otherwise allowed by the vehicle manufacturer.
Lower anchors or seat belts do not rub each other in a way that they interfere with each other. Also please pay close attention to the buckle and any car seats very close to it - we want to ensure the car seat stays buckled.
If you have any questions at all, please reach out to your car seat manufacturer(s) and your vehicle manufacturer, if necessary. These entities are the experts on their products and therefore your child’s safety using them!
Ok, I know the rules and what to look out for! But how do I actually do this?!
Three Car Seats Across Common Questions
Should I use the seat belt?
Absolutely! The majority of the time it makes sense to install three car seats each with the seat belt. Why not LATCH? The lower anchors in the car are spaced exactly 11 inches apart, and usually they’re set closer to the middle of the seating position or the middle of the vehicle bench.
If you used LATCH to install your car seat, you’d be missing out on valuable inches of car-seat-space closer to the vehicle door. It also doesn’t allow for shifting of car seats side to side because the lower anchors are in a fixed position. By using the seat belt to install you have all the space between the belt and the buckle to work with.
Which car seat should I start with?
The first car seat you’ll want to install is your center car seat. Shift it so that it's as close to the middle of the bench as possible – while still being within the center seating position. Most bench seats are not split evenly with 33% in each position.
For example, the VW Atlas is a 60/40 split bench. That means one seating position gets 40% of the total bench. The other two seating positions share the remaining 60% of space. In this scenario, I’d want to shift my center car seat to the side that gives a little extra room to the part of the bench with less space.
What car seat do I put in the middle?
Ideally a forward-facing harnessed seat goes in the middle and rear-facing seats on the outboard seats so it’s easier to access the harnesses. In this set-up you’d harness the children in the outboard (window) seats and then climb into the front seat and turn around to harness your forward-facing child in the center seat.
While not ideal, because an infant car seat can be more narrow than a convertible, combination or booster seat, sometimes the puzzle works best with the infant seat in the center seat. (And then it’s removed either over the top of a low-profile rear-facing seat or across an outboard forward-facing seat.)
Try it out and try again to see which combination gives the most space and access for installation.
What car seats do I need?
If you’re working with a mid-size SUV with a generous bench like the VW Atlas, Chevy Traverse, or Honda Pilot you may only need one or two narrow seats, not necessarily three. I’d recommend replacing the car seat that will be outgrown by your oldest child first so you can pass down their car seat to the younger children. If you purchase one new, narrow, car seat and it’s still too tight, then move on to a second and so-on.
If you’re working with a less-spacious bench seat, you may need three new seats. Don’t forget, three brand new car seats are still more affordable than a brand new car!
Best Infant Car Seats For Three Across
Graco SnugRide Snuglock
Now most infant car seats are relatively narrow. This car seat is a helpful choice because the SnugLock arm closes over the seat belt so you can install it easily next to another car seat. You can connect the seat belt’s latch plate into the buckle with the infant base tilted way out of position and then once it’s buckled, set it into place, remove the slack and simply press down on the Snuglock arm to finish the installation. This can get your installation very, very close to the car door leaving as much space as possible for your center car seat.
Added bonus: a couple of the SnugRide models have a button on the top center of the carry handle (versus two buttons that have to be simultaneously depressed on each side.) This means if you want to take baby out of the car seat, but leave it in the car you can still move the carry handle out of the way. In my three-across set-up I can’t jam my hand between the infant double-button carry handle and the adjacent car seat. I have to take the car seat out of the car, move the carry handle, take out baby, put the carry handle back up, then put it back into the car. (Rinse and repeat again when I’m ready to leave!)
Chicco KeyFit 30
This may in fact be the most narrow infant car seat. The fractions of inches may make a difference in the most difficult of three-across scenarios. The KeyFit base also has a lock-off allowing for a secure close-to-the-door installation.
Best Convertible Car Seats For Three Across
Britax Poplar
At 17” wide and featuring a Clicktight installation, this is the best combination of slim and easy to install. Accommodating a very small infant up to a 49 inch/ 50 pound toddler, this seat gets the job done. Clicktight is a built in lock-off that makes for not only an easy seat belt installation, but a FAST one. I can install this car seat before you can buckle in your toddler!
Graco SlimFit3 LX 3 in 1 (or True3Fit LX 3 in 1)
Screenshot this. Seriously. This is the name of the ultra-narrow Graco seat you’ve heard about. There are a plethora of nearly identically named seats that are 1-2 inches wider than this seat and for three across, you probably don’t want them!
At 16.7” wide this is the seat is your three across best friend. While it’s the most narrow option listed here, it has a couple of downsides you should be aware of.
It’s relatively upright even at its most reclined. If you have a young infant without head control, I’d try this car seat out before buying it. It may not work with the slope of your vehicle seat to be reclined enough. It also can be a little “tippy” when installed rear-facing with the seat belt. A tightly secured seat that tilts slightly isn’t a safety concern, but it can contribute to it sliding around and needing to be tightened once it shifts out of place.
The good news is that in forward facing mode it has a built in lock-off and tends to puzzle well next to other car seats because of it’s low side profile.
Honorable Mention: Clek Foonf/Clek Fllo
The original narrow car seats! The Clek siblings are under 17” wide and puzzle together very nicely to achieve three harnessed seats on one bench. So why are they an honorable mention if they work so well? A stand-out feature of the Clek Foonf and Fllo is that they have rigid LATCH, an advanced safety feature (that you’re paying for!)
When you’re doing three-across you’re using the seat belt 9 times out of 10 and the rigid LATCH feature is going to waste. That said, if you love these seats they are super three-across friendly.
Best Combination Seat For Three Across
Chicco MyFit
The Chicco MyFit is a fan favorite at only 17.5 inches at its widest point. The built-in lock-off (are you catching on to the pattern here?!) makes seat belt installation a breeze.
Arguably my favorite part is that it can keep a child harnessed longer than any other combination seat. But Sam, why is this important? I’m so glad you asked: because puzzling one booster seat into a three across scenario is difficult! It’s far more challenging to buckle a booster seat wedged between two car seats than it is to buckle a harnessed seat.
The downside? It is not compatible with forward-angled non-removable head restraints. (Think Volvo XC-90, Jeep Grand Cherokee L, Wagoneer…) Those types of headrests create a gap that is not permitted by Chicco.
Graco Tranzitions
Also coming in at 17.5” wide (without the optional cupholders) this seat is an excellent contender for three across. Bonus: it’s one of the most affordable car seats for three across! The downside is that it can be challenging to get a tight installation in certain vehicles and it has a narrow belt path that is difficult to fit an adult-sized hand inside of. It also does not have a build in lock-off like all of the other seats we’ve talked about so far.
Best Booster Seats For Three Across
Peg Perego Viaggo Flex 120
The Peg Perego Viaggo Flex 120 is an ultra-narrow booster that makes buckling as simple as can be while next to another car seat. Most boosters have armrests that make maneuvering around to buckle quite difficult. The Viaggo Flex 120 does not!
It’s important to recall that whenever a booster seat is unoccupied it should still be seat belted into the car (or attached via LATCH) so that it doesn't become a projectile in a crash. This seat allows for your booster-aged child to hop out of the car in school drop off and still buckle the seat in with ease.
The seat does also have rigid LATCH to avoid buckling it in while unoccupied. If your vehicle bench has a center latch position, it likely will work in your three across set-up because the booster is so narrow. The base is only 14” wide and the widest part is 17” in narrow mode.
This dream seat has one downside in my opinion… the price. At almost $300 you’re paying the premium for three across here, but at least it has a 12 year expiration. Hopefully all three (or more) of your children will be using it in that timeframe.
Cosco Rise
The good news: this backless booster retails for a whopping $14. It is 15” at its maximum width and fits in most three-across scenarios. This seat does have arm rests though that can make buckling the seat belt somewhat of a challenge. The armrests can also protrude into adjacent car seats because of their location often being in line with the widest part of some car seat’s bases. All that said, for the price of two coffees, it’s worth a shot!
Help! I’ve tried it all and cannot fit a car seat, but I can fit a person. Is it possible to still put my five-year-old here?
Yes! The RideSafer Vest / Travel Car Seat is a wearable vest that positions the vehicle seat belt so it properly fits a booster-aged child. Instead of a booster seat, boosting a child up to fit the seat belt, the vest pulls the seat belt down instead. The travel vest meets the same stringent federal safety standard as every other car seat we mentioned. It is absolutely safe to use in place of a combination or booster seat.
Now that you’re armed with all the info you need to tackle the three-across club, tell us what works for you in the comments below! I’ll go first: #TeamAtlas with a Graco SlimFit3 LX, Nuna Pipa RX and Britax Marathon Clicktight. I’ll be switching the youngest to a convertible car seat soon, I’ll update with what works for me! Kelly already made the swap from an infant seat to a convertible seat for Fred and is currently rocking a Foonf, Fllo, Foonf arrangement across the Tahoe bench.
To see the latest advice on family vehicles, check out my latest posts:
