Best Way To Fit Three Car Seats Across Your Back Seat

If you’re looking for slimline car seat recommendations read – 15 Narrowest Car Seats Australia

So I had a plan to create a super helpful guide to the big question I’m asked from time to time.

How do I fit three car seats across the back of my car?

This isn’t a question I could ever give any advice on myself, because I have two children. Three car seats has simply never been a consideration for me. And honestly I just didn’t put a whole lot of thought into buying my kid’s car seats. Not like I have with prams. And being a pram expert in no way has given me any significant insight into car seats – other than what little I know about car capsule adaptors for travel systems! (Maxi-cosi. It’s almost always Maxi-cosi). But that’s it! I’m really no help at all!

Which is why I went to get some expert advice on the topic from the super helpful staff at Baby Train. The plan was I’d go in, I’d learn a bit about car seats, we’d put a whole bunch of different car seats in my car. I had a vision in my head of a video showing installing various configurations of seats, including for newborns, forward facing seats and boosters.

It was a good plan!

How does the saying go? The best laid plans of mice and men….

Turns out it really wasn’t at all that simple. Apparently my zippy little Kia Rio isn’t really designed for three car seats. It’s POSSIBLE. But it’s not necessarily a great car for showing all the best options because turns out it really is a small back seat. Fine for my two. Not great for three.

three car seats
I’m pretty sure the doors wouldn’t even shut.

So Much To Learn

However! I did learn more about car seats in an hour this morning than I have in nine years of parenting. So I have come back with at least some wisdom to share! And a plan to revisit the super fun car seat montage video I had imagined at a later date – either with some car seats that are coming out soon OR I may need to borrow a slightly wider car for this review. As I said, I have two kids. Fitting three across the back isn’t something I’ve had to account for previously.

AND I will recommend a few narrow car seat options and explain why they are good for fitting three. That said use this as only a very loose guide. The number one piece of advice I’d give after everything I learned today is: Go into a baby store and talk to an expert about YOUR car and YOUR family situation. Because is not a one solution fits all here. I wish I could say “Just get these three seats. Done. Sorted.” But unfortunately it really isn’t that simple! It’s not even quite as simple as just choosing three narrow car seats, or slimline car seats.

Even measuring one side of the vehicle to another and adding up the width of the seats doesn’t give you the complete picture of exactly how each seat will fit up against each other.

Factors to Consider When Fitting In Three Car Seats:

  • Your car. Obvs. It’s important when you measure your car to take the measurement from the armrest to arm rest, not from the door to door. That few centimeters can make the difference between being able to actually shut your car doors.
  • Your Existing Car Seat(s). Unless you’re having triplets you probably already have at least car seat you’re already using. So it’s ideal to try to fit the additional car seat(s) in with what you already have. However, this won’t always be possible.
  • The ages and stages of your children. What car seat types do you need for your children. And not just for right now, but it’s important to consider how long until they outgrow the type of seats you’re choosing. Otherwise you may need to buy additional seats which is costly.
  • Budget. Depending on the factors above you might not actually have a whole lot of choice when it comes to what works or doesn’t work for your car and your families needs. But just remember – no matter how expensive the right car seats are they’re still cheaper than upgrading to a bigger car! So there’s that.

Features To Look For When Fitting Three Car Seats

  • Narrow Car Seats. Again. Obvs. This doesn’t just mean having a narrow base, or a narrow shoulder – but measure it from the widest point. Keeping in mind though that some seats will actually fit in well together and can be adjusted for a narrower fit. But obviously you are looking for seats that are as narrow as possible.
  • Booster Seats Without Armrests. This is something I didn’t consider until I actually had to do it myself. Buckling and unbuckling a child in a booster seat that has an arm rest when they’re pressed up against the car seat next to them is really very difficult. The armrests take up most of that space to put your hand through. So you want a booster without armrests, and if possible that curves in at the base. (See the picture below. Seats are touching, but because there’s no armrest on the booster seat there’s space next to the KidGuard Pro to get a hand in to buckle.)
fitting three car seats
Plenty of space to get to the buckle.

(NOTE: Never use “aftermarket” car seat products like a seat belt extender to make the buckle more reachable, because they haven’t been tested with the car seat for safety and may compromise that effectiveness of the car seat in an accident. It’s just not worth the risk.)

  • Type G Seats. To avoid the issue of having to reach beside the seat to buckle your older child with the lap sash seatbelt there’s the option of Type G car seats. These seats fit up to an 8 year old with an internal 5-point safety harness. So you’ll only ever have to buckle them into the car seat itself. Which is also a safer option.
  • Shoulder Straps That Are Adjustable From The Front. So once you’ve gone through the torture of actually installing your three car seats it’d be great to avoid having to remove the seat and re-thread the shoulder straps as your little ones grow. Look for seats that have a lever to adjust the height, rather than having to unhook and thread the straps each time.

General Tips For Fitting Three Car Seats

fitting three car seats
Leave it to the professionals!
  • Get them fitted by a professional. As I said, there is no one size fits all solution here, so getting that professional advice from a store like Baby Train is really worthwhile. And get them installed by a professional as well. They will have tricks up their sleeve for different seats and configurations. For example; putting seats in a semi-reclined position next to an upright seat so they fit better together.
  • Bring your children along. I know bringing children along on a car seat buying expedition would be hard work! However you need to make sure that the car seats fit your child! You don’t want to buy something that your child will outgrow in a short period of time. It might be worth doing a reconnaissance mission to find a couple of seats that fit your car, and then before buying just test that they fit your kids.
  • Rear Facing As Long As Possible. Long term rear facing is a good idea anyway for the safety of your child. But it can also make all the difference when fitting in those extra seats. When you have the younger child rear facing in the middle that can offer extra shoulder space for the older two either side. Though this may only be a temporary solution depending on the ages and stages of your children.
  • Don’t Force Them To Fit. Car seats can touch each other and they can touch the door, however you shouldn’t be forcing them in. If you need to force the door shut, or if shutting the door causes all the car seats to shake or move then they’re too big for the space. Try a different configuration.

Best Options For Fitting Three Car Seats

fitting three car seats
Matching set – Britax Safe and Sound Kid Guard Pro, Maxi Guard Pro & Graphene

I said I’d get there in the end! Here are some recommendations for what car seats to look for when trying to get to that magic number.

Convertible Car Seats (Newborn to 4 Years)

Britax Safe n Sound Graphene

three car seats 4

Despite looking like a bulky car seat, the Safe and Sound Graphene is surprisingly compact. It’s only 44cm wide, which makes it reasonably narrow. But one of the reasons that this is a great option for fitting in a third child is because it offered the option of longer term rear facing. Which can help with making extra space across the back seat. You can have your child rear facing in the Graphene for approximately 30 months. Around 2 to 3 years. Which is long enough that your older child(ren) may no longer require a booster, thus eliminating the need to fit three children forward facing. Which can be a challenge in some cars. Also the shoulder straps are adjustable from the front using a little lever at the top, which means you won’t have to take the car seat out every time you need to adjust the straps.

Infa Secure Quattro 

three car seats quattro

The Quattro is the narrowest car seat with an inbuilt harness, and it is a tiny 42cm at it’s widest point. Like the Graphene it’s also suitable for rear facing up to 30 months. Which can buy you some time at the very least (maybe you’ll be upgrading to the bigger car in the next couple of years?). And it also has shoulder straps that are adjustable from the front.

 G Type Car Seats (Uses inbuilt harness up to 8 years)

Britax Safe n Sound Maxi Guard Pro

three car seats2

The Safe N Sound Max Guard Pro is one of the best options for fitting three across – and it’s a car seat I’m familiar with using myself. It ticks all the boxes for forward facing babies all the way up to a “large 8 year old” using the inbuilt hardness. So you don’t have to worry about reaching that buckle with your older child. And like the Safe and Sound Graphene, the shoulder straps are adjustable from the front using a little lever at the top, to avoid having to fuss around taking your car seat in and out every time it needs adjusting. It is 46cms wide, so while it is still a very narrow option, it’s one of the widest on this list.

Boosters (4-8 years)

Safe and Sound Kid Guard

kid guard pro

As mentioned before the Safe And Sound Kid Guard Pro is a great option for fitting a booster with three car seats because of the lack of arm rests. It’s been well designed specifically to make getting to that elusive buckle that little bit easier. It’s also a very adaptable booster, with both the head rest and the side guards are able to be adjusted. And it can be expanded to fit up to a 135cm tall child, which is approximately the height of a 10 year old! Which is great if you’re trying to fit for a very tall child, or wanting to extend the time your child uses the booster seat. (Which is a great answer to the OTHER question I’m asked about car seats – “Which is the best booster for a very tall child?”)

Infa Secure Versatile Booster

20180121 102535

I’m including the Infa Secure Versatile Booster, even though it’s not an ideal booster seat, it is super slim and was one of the very few options that could fit that third seat into my small car. It is a TINY 40cm wide at it’s widest point. It’s also extremely easy to put in and take out of your car as it does not have an anchor strap, because it weighs less than 2kgs. That said it’s not a very big seat, it’s not adjustable, it’s basically just plastic – so it’s not necessarily the safest option (though it does pass Australian Safety Standards).

However it would be a good option if you’re not needing to fit three in your car every day, but you just need something light and easy that can fold up and be kept in the boot for the odd occasion where you might be picking up an extra child. It does however have arm rests.

Hope That Helps!

So I hope that helps! I am in no way an expert on the topic, and I’m planning to add to this list as I learn more and as new products become available. However this has been a long time coming, I’ve been asked so many times to write about car seats, and I’m still getting my head around them.

Please let me know if you have any questions – I’ll do my best to answer them! Otherwise if you have any  suggestions, tips or recommendations for fitting three car seats don’t hesitate to comment below!

If you still haven’t found what you’re looking for check out all the Best Car Seat guides

Also feel free to reach out to us for a personalised car seat recommendation!

Rachel Stewart

Rachel is the founder of Parenting Central. She is raising two children, boy and girl, with her partner. Rachel is obsessed prams, car seats, carriers and all things baby. She has worked in the baby industry for several years, for both suppliers and also in a retail setting and has developed a passion for connecting parents with the right products to make their lives easier. When Rachel isn't playing with prams she's enjoys crocheting, drinking coffee (sometimes wine) and spending a little too much time on Facebook.


  1. I have a Pajero 7 seater and have 3 across in the middle row. I have 2 SNS maxi guards and a SNS Compaq mkII (RF).

    Always fit the middle seat first, buy narrower seats!

    1. Parenting Central Yep! We are happy to stick with two, the world seems much friendlier for 2-kid families (plus the thought of having a toddler again makes me feel ill!).

  2. We got caught out when number 2 turned out to be 2 and 3. We managed to get 3 seats to fit when we had one booster and 2 0-4 seats but 3 boosters would not fit, even with the narrowest ones on the market. So we had to get a new car.

  3. 5 seater car here and we have three across. two convertible carseats (one FF one RF) and one convertible booster. all supposed to be slimmer tips besides to let someone else install them ??

  4. We have managed three seats in both our cars okay… but it definitely helped to take our cars to the baby shops and physically test that the seats fit in the car before buying! I don’t think everyone knows that they will let you do this, its very handy.

  5. I just borrowed one of those flimsy boosters for the weekend, because it’s great for when we have an extra kid visiting. It is flimsy and I couldn’t put anyone in one full time but in a pinch, it seems like s good option for occasional use

    1. That’s what we’ve ended up getting as well for the occasions where we have an extra. Nothing else would fit! I wouldn’t want a child in it full time. Even though they do meet safety standards, I also think they’re just not going to be very comfortable!

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