Best Car Seats for 3 Across with Pros, Cons & Recommendations


Welcome to the Best Car Seats for 3 Across Awards!

For the last 2 months I’ve been driving around my 3 kids in our smallest car to answer the question of which are the very best car seats that can be installed 3 across on the market today; meanwhile my husband was kicking back and binge-watching something on Netflix (you owe me a big one honey…)


Finding the perfect car seat for 3 across is not an easy task. Many parents spend weeks researching, testing and comparing all types of car seats. Best of all, I’ve done the heavy lifting for you.

I’ve evaluated everything there’s through the hundreds of miles I’ve driven and listened to the fusses and moans from the back. I’m confident that you will find the perfect seat below because only 6 were left after the 2 months of tests.

I’m ranking these 6 car seats on safety, comfort, how many times you have to curse to install it correctly, coolness factor and of course price.

Frankly picking any car seat from the list below is a guaranteed winner. These are the best of the best that you can choose.

Let’s see those 3-across car seats already!


In a Hurry? Here Are the Top 3 Car Seats to Fit 3 Across


For parents who want the absolute best for their infant and want to comfortably fit it next to the other car seats

For parents who want to enjoy driving without forcing the passenger to kiss the dashboard, even in a Prius

For parents who want to keep their child rear-facing longer while having two more kids in the back

Researched Sources

Reviews Considered


Products Evaluated



#1 Diono Radian 3RXT Convertible Car Seat – Best Car Seat For 3 Across

Best-Car-Seat-For-3-AcrossWe have a WINNER!

Width: 17 inches wide

The Diono Radian 3RXT is by far the best choice if you need a car seat that can easily do 3 across. This car seat has so much going for it, such as excellent safety ratings and comfort that is out of this world.

My kids were falling asleep in this seat all the time, and they are typically full of energy.

I went all-in with this seat and tried it in a tiny Prius. And guess what? It fit, and the front passenger wasn’t even kissing the dashboard.

So, we have a compact size, great safety features, and it’s super comfortable. What else?

The installation is a breeze, and you won’t be tempted to light the car on fire because of the difficult mounting process. So yeah, this seat has it all!

Here is why it’s top of my list:

  • Super Compact Seat: You will be able to do 3-across with ease. Heck, it will fit in a tiny Prius with ease!
  • No Compromises: It’s one of the safest and most comfortable seats you can buy for your child, and it’s a money saver because you can use it for 10 years.
  • Safe from all the Flaws: Not only does it have extended rear-facing so your child is protected in rear-facing mode for a longer time, but also, the seat design has eliminated the floppy head syndrome.

Here are a few drawbacks that you might want to check out:

Hopefully, your kids are clean eaters and are not suffering from car sickness because the fabric is not removable and spot cleaning is your only option.

I wasn’t that happy with the gray fabric because it is not stain-friendly…

All in all, it’s one of the best Diono car seats. It has everything you’ll ever need. Plus, thanks to its slim design, doing 3-across is super easy.

However, since it’s a very popular car seat, it’s hard to keep it in stock. Thus, for your sake, buy it immediately or you’ll risk waiting for weeks on end.

If you’re looking for something cheaper, check out #2 on my list.

This car seat is not only the best for 3 across, but it’s also the best Diono car seat overall.

  • Finally, a car seat where the baby isn’t slouching or sliding down
  • It’s lightweight and easy to move around
  • It’s soft and padded plus it comes with side impact protection
  • The gray fabric is not that stain friendly
  • You can’t remove the fabric; the only solution is spot cleaning.


#2 UPPAbaby Mesa – Best Infant Car Seat for 3 Across

Best-Infant-Car-Seat-for-3-AcrossWidth: 16.75 inches wide

Infant car seats are known to be bulky. Luckily after a lot of research and countless hours of testing, I’ve found the perfect car seat that is the safest and most comfortable while still allowing you to do 3 across.

Can you believe that this beautiful car seat has a width of 16.75”. Yes, it’s true. My 9-month-old sits comfortably in it without reaching the upper limits, and she is a tall girl.

I can’t get enough of the material. It’s so nice and soft that it feels like cotton. Even though we live in a warm climate, my little one was never sweaty, so the materials are breathable.

When it comes to safety this UPPABaby Messa has all the bells and whistles that you will ever need. And best of all, the installation is a breeze. You just press it down until the indicator is green and it’s tight and perfect every time.

Here’s why it’s a must buy car seat:

  • Peace of Mind: When it comes to safety Mesa over-delivers, which means that your baby will be safe from harm and you can drive in peace.
  • Absolute Comfort: The fabric is nice and soft it almost feels like it would be cotton; best of all it will keep your little one cool.
  • Ideal for 3 Across: Your baby will fit in nicely next to 2 other seats because this Mesa has the slimmest width. This way you will be able to travel with ease even with 3 kids in the back.

Also I’ve found a few drawbacks that I have to mention.

The fabric could’ve come in a darker color. The thing is that with this bright fabric the stains are all too visible and sometimes you just don’t have the time to wash and dry it in the afternoon.

Also this is not a cheap car seat. You will need a budget for it and it’s all worth it. You’re getting the best of the best their is.

This seat has won the best slim infant car seat award that allows 3 carseats in a row…

All in all, this car seat is worth its price. Not only will it keep your child safe no matter what but it’s stylish and comfortable even on long trips. Kids typically pass out within minutes, making the driving less stressful.

Even though it’s not a cheap car seat it’s in high demand. The last time I’ve checked there were only a few left in stock. Grab one or you risk waiting for many weeks until the next shipment arrives.

  • Perfect for having 3 across
  • It’s so comfy and soft that my baby has fallen a sleep in minutes
  • It’s the safest infant car seat you can choose
  • The fabric should be darker so stains wouldn’t be visible
  • You need a budget for this seat because it’s pricey


#3 Britax Marathon Clicktight – Best 3 Across Convertible Car Seat

Best-3-Across-Convertible-Car-SeatWidth: 18.5 inches wide

A convertible for 3 across is that even possible? Hell Yes!

After a lot of research and many miles of testing, I’ve finally found the best convertible for the job, and it’s the Britax Marathon.

The width is just 18.5” so you will be able to do 3 across with ease. Besides being narrow although typically convertibles are bulky this car seat comes with every safety feature possible. It even has side impact protection which is rare in convertibles.

Thanks to the revolutionary Clicktight system you can skip the donations in the swear jar. Thanks to it you will be able to get the tightest install each and every time. You can’t go wrong with it. Best of all no Hulk strength is required.

Btw this car seat is grandparent-friendly. Even they can install it with ease so they can safely transport the grandkids.

Did I mention it’s perfect for SUVs?

This Britax is also the best choice if you looking for slim car seats for toddlers.

The material is simply perfect even for warmer climates. My kids never sweated in the Marathon. It’s a breathable fabric so your kids will be comfortable.

There’s no rethreading the harness ever. This is a big plus in my book.

Here’s why it’s a must buy car seat:

  • The Safest Convertible: It’s one of the highest-rated car seats on the market, no wonder because it has every safety feature that you will ever need.
  • 3-across is a Breeze: Since I’ve tested in so many vehicles, it will do 3 across without issues.
  • Fits Perfectly with Most Cars: Besides my small vehicle I’ve tested it with many others from sedans, SUVs and even Cabrio and this car seat fits.

Also I’ve found a few drawbacks that I have to mention.

Kids often have accidents, and with this Britax seat, the cleaning isn’t that easy because it comes with many nooks and crannies. You will need a lot of patience or a very powerful hose to get it spotless.

There’s no denying it that it’s an expensive car seat. However, it’s one of the few ones on the market that offer side impact protection, so it’s all worth it.

This seat has won the best slim fit convertible car seat award while allowing three car seats in a row…

All in all this Britax Marathon is the perfect convertible for 3 across. Besides having a slim profile it has all the safety features and comfort perks that you will ever need.

If you plan to buy this car seat you need to step on it. The stocks are limited and all of a sudden everybody wants this same exact model. If you move now, there’s a strong chance that you will still find one.


  • It’s the most highly rated and safest convertible car seat on the market today
  • Thanks to its narrow profile 3 across is simple
  • Tried and tested in many cars the installation is super simple
  • There are many nooks and crannies so cleaning might be difficult
  • It’s on the priceir side so create a budget for it


#4 Chicco Myfit Zip Air Booster Seat – Best 3 Across Car Seat for SUV

Best-3-Across-Car-Seat-for-SUVWidth: 17 inches wide

“He’s not breathing! Get to the hospital right now!”

No parents should hear these words ever. And yet it was all too common with some friends of mine. You see, their boy had breathing difficulties. If something blocked his air pathways, they ended up in the ER.

The latest trigger was a bad car seat. As kids get older, most car seats offer less and less recline. Eventually, when the child falls asleep, his head will flop. This happened with my friends. So they went on a quest to find the perfect car seat o cure this problem.

The solution came with the Chicco Myfit Zip Air Booster Seat. It has sufficient recline, and they didn’t end up in the hospital ever since. Besides being a comfortable car seat, it has a narrow profile.

That big thing? No way! Yes, that was my reaction as well. This car seat has only a 17” width, so 3 across can be done. If you’re at this stage, then this will be the last car seat that you will ever have to buy.

It won the slim booster seat award while being the best three across car seats choice…

It has two modes harness and booster mode. The upper weight limit is set to 100 pounds. You will be getting a lot of mileage out this car seat.

The Chicco Myfit Zip Air is comfortable, safe, and has a narrow profile. You can do 3 across with ease with it.

  • It’s a heavy-duty car seat that won’t move no matter what
  • Your child will sleep easily without the dreaded head slump
  • It’s well-cushioned, and it won’t overheat
  • It has a narrow profile so thinner kids will be the most comfortable
  • Padding behind the belt not removable for washing


#5 Graco Milestone – Best 3 In 1 Car Seat For 3 Across

Best-3-In-1-Car-Seat-For-3-AcrossWidth: 16.2 inches wide

This happened with our neighbors. They were driving through some country roads on the weekend. Their sun was snoozing in the back. All of a sudden, a huge deer appeared in the middle of the road.

There wasn’t enough time to think. The only thing that the father managed to do is hit the brakes. He could’ve tried avoiding the dear, but then things would’ve got worse. Maybe the car would’ve rolled over who knows.

Instead, they hit the dear head-on. The engine got most of the beating. Of course, the airbags deployed instantly. The car got totaled instantly. There were no injuries. The 3-year-old boy was safe and sound.

The Graco Milestone it’s unique. The width of the car seat is jutted 16.2” which means it’s the slimmest 3 in one car seat that you can get. It has even managed to beat Clek. By being this narrow, you will be able to do 3 across with ease.

This seat won my narrow car seats to fit 3 in a row award  and also it’s the slimmest booster seat…

Besides being narrow, it’s a great 3 in 1 car seat. As you have seen, the protection has been tested in a real crash, and it was flawless. It caters to infants all the way up to 100 pounds. So you’re getting a lot of mileage out of this car seat.

It’s cool and comfortable. With that narrow width, it’s the best choice for 3 across plus it’s the best choice for a narrow booster seat for middle seat.

  • Easy to get baby in and out and it’s easy to move between cars
  • Great dark colors so dirt isn’t visible
  • It’s so safe it has probably designed by a mom
  • There’s no good harness holder you will waste time strapping in
  • If you have large hands, it will be difficult to loosen the straps


#6 Graco Tranzitions – Best Budget Car Seat For 3 Across

Best-Budget-Car-Seat-For-3-AcrossWidth: 17.4 inches wide

This incident happened with a friend of mine. She was driving her daughter home from ballet class. Everything was the routine.

Then they stopped at a red light. A drunk driver slammed into them from behind. To make things worse, the crash happened at 50 mph.

The impact was loud. The trunk pure and simply evaporated. The back seat has bent into an unnatural angle.

The mother is fearing the worst checked on her daughter. She was fine. There wasn’t a scratch on her. She was shaken up. Otherwise,e she was OK.

When you’re on a budget, or you want a secondary narrow car seat, the Graco Tranzitions is a great car seat to have. As you’ve seen above, this affordable car seat saved the life of a little girl.

It’s the cheapest 3 in 1 car seat that you can get. It has a slim design. The width is just 17.4” wide. For an affordable car seat, you’re getting your money’s worth. It caters to toddlers who are at least 22 pounds all the way up to 100 pounds.

This Tranzitions car seat could be the last one you will ever buy.

If you can spare less than a half-inch, then this car seat will be a great 3 across the seat.

  • Finally, a super lightweight car seat that’s easy to transition in and out
  • It has a narrow profile so three car seat can be fitted in the back
  • The cushion gives extra comfort, so it’s good on long road trips
  • The armrest feels short you can only utilize them in backless booster mode
  • It’s not the prettiest car seat around it gives a cheap feeling

Related: The best car seat for tall 4 year old reviewed


Buyer’s 3-Across Car Seat Guide

Hell of a trip, wasn’t it? I thought about what would be a great compliment for this article. Then it popped into my mind that a buyer’s guide would be a great bonus. Maybe in the future, you would be able to put it to use.

Parents literally spend weeks, if not months sorting through all the car seats. By having this go-to guide, you can eliminate those car seats that are not interesting and only spend time with those that might be a good fit.

Before we can get to that, there are a few things I have to mention.

Once you get the car seat, you have to decide where you want to mount it. The safest place is in the middle of the car. Yes, I’ve heard this over and over again. That’s impossible. OK, no problem, I have another place which is the second safest one. It’s located behind the driver.

Getting the right install is crucial. If not, then the car seat won’t be able to give the maximum potential. According to a recent study, 75% of car seats in the US are installed poorly. That’s troublesome. So many kids are riding around without the necessary protection?

This is why you should reach out to a licensed professional if you have any doubts. I’ve just noticed that Amazon is offering it as a service for a fee. So now you have no reason not to have a safe install.

It’s time to get this buyer’s guide started.


Safety for the best car seats to fit 3 across

This is the #1 item on my list. This is where all begins. Car seats exist to keep kids safe. Currently, on the market, there are only safe car seats. If there are issues, they are recalled immediately.

To get on the marketplace, the seats have to pass the government tests. The good news is that all of them pass. The bad news is that there are a few brands that barely cut while others over-deliver. Now, which one would you like to protect your child?

My best advice here is to get the safest one that you can afford. The best one is the one that offers both side impact protection and rollover. Though there are only a few that offer these two.

Side impact protection comes in different layers. The most common one is between 1 and 3.


Size Limits for a slim carseat

This is my favorite place to save money. Yes, there’s a secret, and I will share it with you in a minute. Let’s face it. These car seats are expensive. Plus, they have a short expiration date. Not to mention that are outgrown way too fast, so that’s money out of your pocket.

The secret to saving money is to plan ahead. If you buy the car seat for a longer period, you will be saving money. Also, this is why all in one car seats are so popular nowadays. You buy it once and will serve your child until they don’t need the car seat anymore.

Here you should check the weight. If you have to swap it between cars, it’s good to know if they are heavy or not.


Install skinny car seats

This is the biggest issue with car seats to get the right installation. To make it fair, all brands strive to make the installation as easy as possible.

Even so, there are so many car seats poorly installed. No matter what read the manual, that’s why it’s included. If something is not clear, then check out YouTube, you can probably find a better installation video.



This is the last point on my list. We all know how kids are. They leave a mess and tend to have accidents. Now from all the car seats above, the Clek family is not machine washable. They only allow spot cleaning and you have to buy things from them.

This is the end of my buyer’s guide.


Best 3 across car seats conclusions

We have reached the end of the best car seats for 3 across article. It was a long journey. By now you should know which car seat is the right fit for you.

It’s your move now get the right one as soon as possible because the last time I’ve checked, the stocks were running low.

I would love to hear from you. Maybe you have some experience with different car seats then share them below.


Frequently Asked Questions (FAQ):

Can you fit 3 carseats in a full size car?

Yes you can fit 3 carseats in a full size car however you need to pick the right seats for the job. For this purpose you will need to use narrow or slim car seats. Check the base width and multiply it by and then measure the back seat and see if it fits.

Do Diono booster seats fit 3 across?

Yes, Diono booster seats can and will fit 3 across. Even though they look big their base is not that wide so you can do 3 across with ease. I’ve tried it and tested it myself.

How do you place 3 car seats in a row?

To place 3 car seats in a row you can use the following option. You can place the rear facing car seats to the side and the booster or forward facing car seat in the middle. Typically the older child sits in the middle (best car seat configuration for three).

Which car seats are perfect for fit three car seats across?

All of the above car seats are good for fitting three across. Depending on the age and weight you can choose which one of them is the best fit to do seats fit 3 across. Which car seats convertible seats fit 3 across? The Diono Radian would be the winner.

Which car seat didn’t make it on the list?

The Chicco Keyfit barely missed the list.

Which booster seats can do three car seats across?

The narrow seats can do this. Since they are boosters seats you can use rear facing mode. Rear facing mode is for the convertible car seats for small cars. These are all safe car seats. You can use the seat belt or the vehicle seat belts to make the right install.

What safety features can you expect from boosters seats that can do three seats?

Maybe you have a new car or a bigger family and you need great 3 car seats across.  Don’t forget the cup holders. The latch connectors will work until booster mode after that you have to use the seat belts.

Which car seats (booster seats) would be a good alternative for the list above?

These car seats / booster seats would be good alternatives: clek oobr booster seats, primo viaggio infant seat, maxi cosi mico max 30 infant seats, immi go belt-positioning booster seat. The mico max 30 infant car seats are a great choice for middle seat and rear seat.

Can you fit 3 infant car seats across?

Yes you can fit 3 infant car seats across if you pick one from the above list. The infant seat doesn’t really allow a lot of wiggle room. As you know infant seats come with an infant insert. The weight ranges for a new car seat is between 4 and 35 pounds.

Can you fit 3 booster seats across?

Yes there are multiple booster seats that allow to fit 3 across. The list above can help you. The drawback of these seats that bigger kids might not have sufficient hip room, shoulder room, leg room. You get the best weight range with these car seat types.

How is the car safety ratings with these car seats?

I know how important are car safety ratings. This is why I have only picked seats that have high car safety ratings. The car seat manufacturers go out of their way to offer the most protection possible. These child seats go through serious crash tests. And only those are allowed to be sold which have high crash test ratings. As you know crash forces are vicious during an accident. This is why you need the best protection possible. If you need a car seat guide then reach out to a local child passenger safety technician and check with local car seat laws. Typically these car seats are meant to be installed on the back seats. This can be done with the seat belt or the latch anchors. As you know the seat belt installation is the slowest. Also there are the tether anchors for added protection and child restraints. The harness straps are padded so your kids don’t get hurt during powerful crash forces. Most infant seats can be installed without the base. The seat without base install can only be done with the seat belt. Other features to check out would be: seat belt buckles, base width, bucket seats, recline adjustment, cup holder.

How can I fit 3 across car seats in most cars?

There’s some science to fitting 3 across car seats in most cars. It’s incredibly easy in a larger vehicle while while it’s challenging in small cars. In midsize suvs there will be very little room between the front seat and the one row. What we have done is we moved the oldest child to to front seat plus we still have third row access. Two convertible seats fit nicely side by side only the middle seats will be crammed especially with smaller vehicles. This is why you should check out narrow car seats some even have rear facing seating positions. If you have very little room in your midsize SUV then consider the highback booster with latch installation for extra space. Most kids will be comfortable in the front seat where you won’t need the narrowest seats.

What is the most need to know info about 3 across car seats in most cars?

The most need to know info about 3 across car seats in most cars is as follows. Always consult with child passenger safety technicians if you’re not sure about the mounting. For center seating position it’s a good idea to check a bucket seat. Always check the latch weight limit even with platinum models. If there’s a load leg use it because it’s a life saver. Other features to take into count: lower latch anchors, rigid latch, harnessed seats, head restraints (head restraint), lower anchors, forward facing bucket seat and forward facing convertible seat. Plus there are other seats to choose from (other car seats) for the back seat.

How to choose new car seats for young children?

The bad news is that most seats work with most cars and most kids. If you have a smaller car then you will need a narrow car seat. Also you can choose from backless booster seat, forward facing bucket seat, convertible seat or even a highback booster with lower anchors. Some seats are a bit heavier which might be because of extra safety. These seats work in seats work and in one row.

Which are the best slim car seats on the market today?

The best slim car seats (slim car seat) are as follows, plus what car seats fit 3 across:

  1. Diono Radian 3RXT – best 3 in 1 booster seat with 3 in a row car seats option

  2. UPPAbaby Mesa – best infant slim fit car seat

  3. Britax Marathon – best slim fit booster seat

  4. Chicco Myfit – best 3 across booster seats and booster seats that fit 3 across

  5. Graco Milestone – best for 3 car seats in a row and slim car seats for 3 across

  6. Graco Tranzitions – best narrow booster seat

These would be the best car seats 3 across that will fit in most cars and car seats that fit 3 in a row.

Which are the slimmest car seats for 3 across?

The slimmest car seat for 3 across are:

  • Britax Marathon

  • Graco Milestone

Which are the best convertible car seats that fit 3 across?

The best convertible car seat that fit 3 across are:

  • Diono Radian 3RXT

  • Britax Marathon

What is the best booster seat for 3 across?

The best booster seat for 3 across is the Chicco Myfit. This car seat are the best narrowest car seats?

The best narrowest car seat is a Diono Radian 3RXT. This car seat will fit in most cars.

Which is the best infant car seat for 3 across?

The best infant car seat for 3 across is the Britax B-Safe 35 Infant Car Seat. This car seat will fit in most cars.

Which car seats can fit 3 across?

The car seat that can fit 3 across are:

  1. Diono Radian 3RXT Convertible Car Seat – Best Diono 3 across

  2. UPPABaby Messa – best car seats for three across

  3. Britax Marathon – best car seats that can fit 3 across

  4. Chicco Myfit Zip Air Booster Seat – chicco myfit 3 across

  5. Graco Milestone – best slim car seats that fit 3 across

  6. Graco Tranzitions – best car seat to fit 3 across

Why isn’t the Graco Slim Fit on the list?

The problem with the Graco Slim Fit is that only the name says that it’s slim however there are far better choices for 3 across than the graco.

Which are the 3 across car seats for chevy equinox?

The best 3 across car seats chevy equinox could be any one of the above-mentioned car seats. It comes down to your kids and what stage they are in. Even if you pick the biggest car seats from the list above they will fit your chevy equinox.

What are the narrowest booster seat options available?

The narrowest booster seat options which are also three across booster seats are:

  1. Cosco Topside Backless Booster Car Seat – 15 inches

  2. Graco TurboBooster Backless Booster Car Seat – 16 inches

  3. Graco Affix Highback Booster Seat – 16.5 inches

Which is the best car seats for 3 across infant car seats?

The best for 3 across infant car seats would be the Uppababy Messa.

What are the best cars that fit 3 car seats?

The best cars for fitting 3 car seats include minivans or SUVs, as their larger size makes it easier to securely install 3 car seats. The Honda Odyssey, Chrysler Pacifica, and Toyota Sienna are all excellent examples of vehicles with enough space to safely seat up to three children at once.

What is a slim car seat?

A slim car seat is typically an infant or convertible seat that has been designed to be able to accommodate three across installations in smaller vehicles. Slimmer models tend to have narrower widths than average while still meeting safety standards and offering the same quality protection.

Are there any boosters available for three in a row situations?

Yes, some booster style car seats are specifically designed for three across installation. These often feature narrow backrests and contoured sides which make them narrower overall than standard boosters but still offer the necessary level of safety for your child’s age group. Some notable examples include the Graco Affix Youth Booster Seat and Accordion’s EZ Fit Three-Across Booster Seat System.

Can I install two forward facing car seats in the passenger side of my vehicle?

It depends on which type of vehicle you have but generally speaking, yes it is possible to install two forward facing car seats on one side in most regular sized passenger vehicles like sedans or station wagons so long as both fit into adjacent spaces without hitting each other or blocking access points such as rear windows or doors. However it’s important to always consult your vehicle manual before attempting this kind of arrangement.

Last Updated on October 25, 2023 by Brian Beasley

Written by Linda Reid

Hey there, I'm Linda, a mom of three cool kids. I've tried so many car seats, you could call me a "Car Seat Detective." Searching for the perfect car seat can feel like finding a needle in a haystack, but don't worry! I've committed to researching and reviewing car seats that are super safe, cozy, and great for growing kids. Together, we'll find the perfect car seat that keeps your child safe and cozy, and makes you feel like a super-parent!