12 Narrowest Convertible Car Seats [16″-19″] – 3 Across

One of the most challenging and also satisfying parts of doing CarSeatOn is figuring out which car seats will work best to meet your needs. 

If you’re looking for the narrowest convertible car seats, move on to read this guide, in which we narrow down the options and find the best recommended narrow car seats in tight side-by-side or 3 cross situations

Convertible car seats are considered the bulkiest among the five car seat types. There are very few narrow convertible car seats on the market. But we find the narrowest convertible car seats that are all under 19 inches wide

To make the list, a narrow convertible car seat must also meet some other criteria: 

  • Size and shape: a seat must be narrow enough under 19″ but also fit well next to other car seats
  • User-friendly installation with the seat belt
  • High enough height and weight limits for a few years of use
  • Roomy enough for comfort for growing kiddie

 

To make it simple, we categorized the 5 narrowest convertible car seats into three groups of car seats based on the width of the car seat: 16-17” / 17-18”/18-19”. Just click on it below to find the one best fit your needs.

Graco SlimFit3 X Fit 3 Across

Narrowest [16-17"]

Narrowest Convertible Car Seats to Fit 3 Across

17″

Clek Foonf Convertible Car Seat
Clek Foonf

$549.99

Narrowest [17-18"]

Narrowst Convertible Car Seats Probably Fitting 3 Across

17.5″

Safety 1st Jive Convertible Car Seat
Safety 1st Jive

$99.99

Narrowest [18-19"]

Narrowst Convertible Car Seats Not Fitting 3 Across

18.5″

Britax Marathon ClickTight Convertible Car Seat
Britax Marathon ClickTight

$299.99

16-17"

Narrowest Convertible Car Seats [16-17"]

17-18"

Narrowest Convertible Car Seats [17-18"]

18-19"

Narrowest Convertible Car Seats [18-19"]

We also make several lists of the narrowest convertible car seats according to their performance (rear-/forward-facing/booster weight/height limits), by budget, and by bonus features (like lightweight, portable for travel)

By Weight Limit

See Our Top Picks Organized by Size Limits from 4 to 120 lb

By Height Limit

Best Choices Organized by Height Limits from up to 57 inches

By Price

See Car Seats Organized by Price (Prices Start under $100)

By Bonus

See Car Seats by Bonus features (e.g. for travel etc)

Narrowest Convertible Car Seats between 16" and 17"

Graco SlimFit3 LX - Narrowest 3-in-1 Convertible Car Seat

Graco SlimFit LX 3-in-1 Car Seat

Graco SlimFit3 LX - 16.75"

Key Features
The Good
The Bad

$279.99

Graco SlimFit3 LX stands out of the super narrow car seat and it is the narrowest convertible car seat on the market. It has an impressive narrow footprint and width, measuring only 16.75″ wide.

This width is even narrower than the Diono Radian 3R, which is well-known for its slim design and ranks #2 on this list. 

The SlimFit3 LX is an upgraded version of its previous sibling called SlimFit. The latter is a slim design with a width of 20 inches. It’s not that slim compared to these narrowest models. 

Graco SlimFit3 LX features a built-in seat belt lock-off. You can make use of it for fast installation for forward-facing through the 5-point harness and booster time. It’s a pity that the seat belt lock-off does not work for rear-facing installation.

So it’s not ideal for a center installation or side installation with the seat belt. That means it may take up more space from the sides in a tight 3-across situation. But it is worth a serious try for its 16.7-inch super narrow width. 

Graco SlimFit3 X Fit 3 Across

The Graco SlimFit3 LX is a good narrow convertible car seat for growing children, starting from 4 pounds to 100 pounds until he or she reaches 57 inches tall. The 40-lb weight limit makes it one of the best car seats for extending rear-facing, up to 2 years or older.

You won’t be surprised that the Graco SlimFit3 LX has a long lifespan of up to 10 years. The company set up this limitation to match its position as an all-in-one car. But the real usable time maybe not be as long as 10 years because the lifespan started to be calculated from the date of manufacture, not the date you purchased it. 

The Graco SlimFit3 LX is one of the narrowest convertible car seats that are both child-friendly and parent-friendly. 

It is one of the safest car seats. More than the seat belt lock-off for secure and tight installation, it features the ProtectPlus engineering to deliver optimal protection from the front, side, rear, and rollover crashes. The high-strength steel frame and plenty of energy-absorbing foam make a solid build to enhance the protection.

Graco SlimFit3 LX Install in Vehicle

The included infant insert is good to keep your newborn baby comfortable and steady in the car seat. It’s removable and offers a spacious room as your baby grows bigger.

Two cup holders are useful to store their drinks or snacks or toys, making them happy to stay in their own safe tiny cavern.

Made of machine-washable fabrics, this super narrow 3-in-1 convertible car seat is nice for busy parents. I’m sure that you would be happier to get a Graco SlimFit3 LX because of its ‘Rapid Remove’ cover. Yes, this affordable all-in-one convertible car seat features the same seat cover design as Graco 4Ever DLX 4-in-1 car seat.

With the Rapid Remove design, you can easily take off the seat cover in seconds and set it back into the car seat very quickly.

Multiple colors are available for choice. We do recommend Kartina if you have a baby girl. It’s one of the best purple car seats for girls.

Diono Radian 3R - Foldable Narrowest Convertible Car Seat

Diono Radian 3R 3-in-1 Car Seat

Diono Radian 3R - 17"

Key Features
The Good
The Bad

$199.99

The Diono Radian 3R is one of the narrowest convertible car seats. The extremely low profile, narrow width, and shallow sides make it an excellent option for fitting 3 across.

With a slim design and narrow width at only 17″, the Radian 3R tucks in nicely next to other car seats, both rear-facing and forward-facing seats. It works well in the center with two other super narrow car seats on either side.

The Radian series are designed with a slim body. They are all narrow all-in-one car seats with the widest part being only 17 inches. This width can fit 3 across in most vehicles.

It’s just the car seat height that may cause a problem when installed rear-facing, taking up much space from the front passenger or driver seat.

The Diono Radian 3R is easy to maneuver around and friendly for kids to climb in and out, due to the Radian’s low-profile shape. It’s easier to get an infant carrier out of the center of the Radian installed on the side forward-facing compared to those higher forward-facing seats like the Graco SlimFit3 LX

Diono Radian 3R Fit 3 Across

It’s one of the best car seats for extending rear-facing due to the 50-pound weight limit and the 44-inch rear-facing height limit. This means even a 95th-percentile boy can use this car seat rear-facing until his 4th birthday.

But installing Radia 3R rear-facing can be very tricky.

If you install it with the seat belt, you probably can not get a tight installation. But if you install it with LATCH, it may not fit 3 baby car seats in the same row unless the other two car seats are super narrow as well. So you’ll see three Radian 3Rs in the back seat, side by side, rear-facing, or forward-facing. 

This narrowest convertible car seat is also one of the most portable car seats due to its folding design. Fold the seat pad up and tie it, the depth reduces to 9″ (20.3 cm). You can easily carry it like a backpack. If you want to store it for the next child, it won’t take up as much space as those unfoldable car seats. 

It’s a cheap car seat with narrow width, priced under $200. The Radian 3R has a good size limit to grow with your child from birth to 7 or 8 years old when they don’t need a car seat. It’s a real money saver. 

But it’s not perfect. Lacks infant insert or body support for newborns. Feature only two reclines for adjustment. That’s not enough for finding the right angle for the most appropriate fit for newborns under 6 months.

Car Seats Comparison Radian 3R Radian 3RX Raidan 3RXT Raidan 3QX Radian 3QXT
Price $199 $269 $329 $369 $399
Weight limits (lb) RF:5-50 / FF: 22-120 RF: 5-50 FF: 22-120 RF: 5-50 FF: 22-120 RF: 4-50 FF: 22-120 RF: 4-50 FF: 22-120
Rear Facing Weights Up to 50lb Up to 50lb Up to 50lb Up to 50lb Up to 50lb
Newborn Protection - - 2-in-1 Advanced 3-in-1 Advanced 4-in-1
Safe+ Engineering - - -
Head Support - 12 Positions 12 Positions Safe+ 12 Positions Safe+ 12 Positions
Cup Holder -
Fit 3-across
Width (in.) 17 17 17 17 17

Clek Foonf - Narrowest Convertible Car Seat with Stylish Design

Diono Radian 3R 3-in-1 Car Seat

Clek Foonf - 17"

Key Features
The Good
The Bad

$549.99

The Clek Foonf is one of the narrowest convertible car seats with a streamlined design. But the inside is very roomy and comfy for growing kids.

The Foonf is very similar to the Diono Radian 3R, slim and low-profile. Good for kids easily climb in and out. But it performs better than its competitor for a tight installation and is very slightly slimmer than the Raidan 3R (16.9″ vs 17″, you can not see this difference or even can’t feel it anyway).

The Clek Foonf can be easily installed with the seat belt in both rear-facing and forward-facing, making it one of the safest car seats. The Foonf can sit fairly upright (older kids often prefer to sit more upright in the car), not taking space from the front seat. So it’s a great choice for placement behind even a taller driver or passenger.

Foonf can be used rear-facing until a child is 44 inches or 50 lbs, the same as the Diono Radian 3R. This means most kids can use this seat rear-facing until he or she grows to 4 years old. 

The mandatory anti-rebound bar not only is good for newborns for protection but also offers lots of legroom for older kids. 

The Clek Foonf is a very expensive narrow convertible car seat, priced over $550. That’s not a good option for multi-child families that have a tight budget for this gear. Having three Foonfs in the back seat will cost almost $2000. It’s not friendly for most families.

So it’s not our best recommendation. There are cheaper alternatives, like the Graco SlimFit3 LX and Diono Radian 3R. They are also the narrowest convertible car seats but at an affordable price of under $300 or even under $200.

If you have enough budget, we recommend you get a Doona. It’s in the same price range but the only car seat with four wheels and combines an infant car seat and stroller into one. Or you can try the Britax One4Life.

Narrowest Convertible Car Seats between 17" and 18"

Safety 1st Jive Convertible Car Seat

Safety 1st Jive - 17.5"

Key Features
The Good
The Bad

$99.99

Safety 1st makes cheap car seats, and this Jive narrow convertible car seat option is no exception. Coming in at 17.5″ wide at its base and 18.13″ wide at the torso, this is a versatile and reliable narrow car seat that will last you many years of comfortable riding.

Not to mention the friendly low-profile style and high-quality manufacturing! Yes, it is wider at the torso than other car seats on this list, but the super narrow 17.5″ base makes sharing backseat space with a rear-facing infant car seat much easier.

In rear-facing mode, it can be installed to the included flexible (non-rigid) LATCH connectors or using the vehicle’s seat belts.

Without any luck, the Safety 1st Jive does not have any rigid LATCH connectors or integrated belt lock-off for installation. That’s why you can find most parents complain that it’s harder to install the Safety 1st Jive. This case does not change in the premium Grow and Go all-in-one car seat.

Note that once your child reaches 35 pounds, you’ll need to transition away from LATCH to the vehicle’s seat belts. Because there are no integrated lock-offs in rear-facing mode, you will be best served by installing the LATCH until your child reaches 40 pounds.

This will help you get a relatively stable install, which is challenging to achieve with the vehicle’s seat belts in rear-facing mode. 

Once you transition to front-facing, you will need to use the vehicle’s seat belts. We had some challenges installing this car seat next to a door when another car seat was in the middle position, especially when using the vehicle’s seat belts in rear-facing mode.

It also protrudes very far from the back seat, limiting front seat leg room when placed anywhere other than the center position. For basic specifications, the Safety 1st Jive convertible car seat can support babies and toddlers from 5 to 40 pounds (and top of the head at least 1″ below top of the headrest) in rear-facing mode, which is extremely useful given the new recommendation by the American Academy of Pediatrics that children should be rear-facing for as long as possible (beyond their second birthday)

This is one of the reasons we love both the Radian (above) and this Safety 1st Jive so much. Forward-facing, this narrow convertible car seat can be used from 22 up to 65 pounds. It does not additionally convert to a booster, so keep that in mind when choosing between this and the Radian

Regarding safety factors, Safety 1st Jive uses energy-absorbing foam and side impact protection; but its narrow contact with the back seat doesn’t help much with stability when installed close to a door.

Overall, this is a great option for the narrowest convertible car seats with some great features, and it’s one of the best convertible car seats available in general. 

Narrowest Convertible Car Seats between 18" and 19"

Britax Marathon ClickTight - Narrowest Convertible Car Seat of Easy to Install

Britax Marathon ClickTight Convertible Car Seat

Britax Marathon - 18.5"

Key Features
The Good
The Bad

$329.99

This is Britax’s narrowest convertible car seat. Not nearly as narrow as its competitors, and perhaps not appropriately named, the Britax Marathon is 18.5″ wide at the base without a cup holder adding the width. Yes, the Britax Marathon is a car seat without cup holders.

But it is still the widest convertible car seat on this list! So why are we including it here? Two reasons. First, parents commonly ask us whether the Britax Marathon is a good option for fitting three car seats in a row. Second, it features the ClickTight technique to be the easiest and best narrow convertible car seat with seat belt installation

In general, the Britax Marathon can help you fit three in a row in a larger vehicle, like a full-sized car, SUV, minivan, or truck, but it might not help you fit three car seats in a row in a relatively normal-size vehicle or small cars.

Britax Marathon certainly supports both the LATCH and seat belt installation methods. But it’s strongly recommended to use a seat belt. It’s the best way recommended in the user manual. Why? 

The ClickTight technique takes the seat belt installation to the next level. You can achieve a truly tight and proper installation in minutes. 

Plus, installation with the seat belt has no weight limit, is very different, and is more efficient than the LATCH.

As we were testing the seat in a three-across configuration, we were puzzled by how some sites recommend the Britax Marathon as a narrow convertible car seat. It’s not very narrow at all, but the stable installation with the vehicle’s seat belt helps to keep it fit tightly. 

We definitely do not recommend using this seat in tight three-across scenarios, or you’re only going to install it in the center seating position. Even then, you’ll need to have a larger vehicle to make this fit. Overall, not great for fitting three in a row in most situations.

Buying Guide to Choose the Narrowest Convertible Car Seats

Check the Car Seat Width

If you want the narrowest convertible car seats to fit 3 across, the ideal width is between 16 inches and 17 inches. The Diono Radian car seats are 17 inches wide at the widest shoulder rest part, the seat pad is only 12 inches. 

However, very few convertible car seats are as narrow as them. Only Graco SlimFit3 LX performs the best. It’s only 16.75″ wide.

Infant car seats are averagely narrower, but they don’t last as long as convertible car seats. 

Booster seats can be wide or narrow, depending on the type, make, and model. Backless boosters are the narrowest option to make it much easier to get 3 across.

Plan Where to Install the Car Seat

The position of the car seats may affect the final result to fit 3 car seats across. The center of the back row is probably the narrowest spot (and also the safest).

But it lacks LATCH in some vehicles. So you need to check if the vehicle seats have LATCH or not and confirm their location. 

You may not be shooting for 3-seats across unless you have got the narrowest convertible car seats.

“Narrow” Features

If your family owned a compact European vehicle, the narrowest convertible car seats should be the best option for achieving three seats across. Better to have bonus features if the narrowest convertible car seats:

  • Removable and collapsible cup holders, those that squish in when not being used
  • Straight sides
  • Seats that are narrow at the base but may be wider higher up in the shoulder or torso
  • Adjustable seats like the innovative hi-fold

Size of Your Car

If you have a small car, achieving the 3 across fit can be a challenge. Based on the narrowest convertible car seats between 16 and 18 inches wide, the back of your vehicle should be at least 51 inches in total to get 3 seats across. 

The wider, the better!

55 or 60 inches would make it much easier. Minivans, large-size or mid-size SUVs, and full-size cars are good options. Small cars like sedans just aren’t quite wide enough.

The simple but efficient way is to check the hip room and shoulder room on the back seat or second row (the third row is not spacious for fitting 3 across). 

The second row of the Honda Civic is 47.3 inches wide at the hip and 55 inches across at the shoulders. Toyota Corollas have hip and shoulder widths of 51 inches and 54 inches. The Ford Focus comes in at 52.7 inches of hip room and 54.7 inches of shoulder width.

Compare those numbers to larger vehicles.

The Honda Odessy minivan’s second-row seat is 63.5 inches across at the shoulder and the new Ford Explorers are 61 inches across.

Midsize SUVs are similar. For example, the Ford Edge is 61 inches, the Jeep Cherokee is 58 inches, the Subaru Ascent is 60.3 inches and the Nissan Murano is 58.8 inches across.

Use LATCH and Vehicle Seat Belts for Installation

If all the car seats come with the same form of harness, then the vehicle seat buckles don’t have to be easily accessible.

That makes your life much easier. No need to learn about the difference between car seats (But we strongly recommend you read the user manual in pdf or video).

So, where possible, choose the narrowest convertible car seats that can either be installed one time with the LATCH system and/or are connected to the vehicle seat belt.

In this way, the parents do not have to be able to find the seat buckle between child safety seats each time they buckle up.

Other Narrow Convertible Car Seats Not Reviewed Above

Wdith Car Seat Price Weight and Height Limits
19 in. Britax One4Life ClickTight $399.99 120 lbs/63"
17 in. Diono Radian 3QXT $449.99 120 lbs/57"
15.5 in. Combi Coccoro $237.99 40 lbs/40"
17 in. Cosco Mighty Fit 65 DX $89.99 65 lbs/49"
17.5 in. Baby Trend Trooper $119.99 65 lbs/50"
18.5 in. Evenflo Sonus 65 $119.99 65 lbs/49"
17 in. Evenflo Tribute LX $279.99 40 lbs/40"

Narrowest Convertible Car Seats Safety

The car seats mentioned in this article are safe. They have met or exceeded governmental safety standards.

The major safety features like head and torso protection and side-impact protection are not as related to the width of the seat as they are to the materials like frame (plastic or metal) and foam, and most importantly, the installation.

The proper and tight installation will ensure 99.9% or more safety.

Basically, the narrowest convertible car seats have two layers of head and side impact protection, a reinforced steel frame, energy-absorbing foam, a 5-point harness, and many other features that reduce the motion of a child in an incident and absorb crash energy into the seat itself.

A narrower design doesn’t necessarily mean less safe. The Graco SlimFit3 LX is a good example. It’s the narrowest convertible (all-in-one) car seat but is packed with advanced safety features like Graco’s ProtectPlus engineering.

Britax One4Life Install in Vehicle

However, some of the luxury convertible car seats with the very most safety features are the bigger, heavier models.

Car seat designs that aren’t targeting a narrow fit may add extra layers of impact protection, like the Britax Advocate and One4Life. Some features like anti-rebound bars (ARBs) or load legs may be available on narrow or wider seats, you have to look at them individually.

While you may be concerned that a car seat doesn’t have every safety technique ever invented, don’t be! You’ll be a lot more satisfied buying a car seat that is practical and convenient. Keep in mind that the majority of safety issues are related to installation and misuse, not seat design.

Things to Consider for the Narrowest Convertible Car Seats

Buying child safety seats is always not an effortless job. There is a large selection, making it more difficult to find the perfect car seat to suit both your and your child’s needs.

More than that, you should also consider how the car seats interact with each other. If you have to ride two or three children, narrow car seats are preferable, just make sure they will work side-by-side to fit your needs.

For example, does a rear-facing infant seat fit between two front-facing convertible seats? The seats must all work well together for the seats to fit.

Also, always consider your budget when purchasing a narrow convertible car seat. The lowest-priced item may not be the best financial choice, the Safety 1st Jive for example. 

Read the reviews to ensure good quality, and more importantly, ease of installation. You don’t want to have to buy a new seat that is difficult to install, because they probably don’t work well to achieve our expectation – to protect the precious little one.

High quality usually means durable. Buy a quality car seat from the start that will last you a few years until it expires.

Car seat width is a big concern for large families and families with smaller vehicles. Thankfully, it is now easy to find options for every budget.

Narrowest Convertible Car Seats by Size Limits

By Weight and Height Limits

Weight Limit Car Seat Price Height Limit
65 pounds Britax Marathon $299.99 49 in.
65 pounds Safety 1st Jive $99.99 49 in.
65 pounds Cleck Foonf $549.99 50 in.
100 pounds Graco Slimfit3 LX $279.99 57 in.
120 pounds Diono Radian 3R $199.99 57 in.

*Price may change on the e-commerce platform due to promotional sales.

Narrowest Convertible Car Seats by Price

Rank Price Car Seat Weight Limit Height Limit Stage
1 $99.99 Safety 1st Jive 65 pounds 49 in. 2 stages
2 $199.99 Diono Radian 3R 120 pounds 57 in. 3 stages
3 $279.99 Graco SlimFit3 LX 100 pounds 57 in. 3 stages
4 $299.99 Britax Marathon 65 pounds 49 in. 2 stages
5 $549.99 Clek Foonf 65 pounds 49 in. 2 stages

Narrowest Convertible Car Seats by Bonus Features

Cheapest:

Best for Travel

5-point car seat up to 120 pounds

Longest Extendable Rear-facing:

FAQs – Narrowest Convertible Car Seats

What is the narrowest convertible car seat you can buy?

Graco SlimFit3 LX is the narrowest all-in-one convertible car seat you can buy. It’s 16.75” wide. It’s an affordable narrow convertible car seat. 

But if you want a cheaper alternative, the Diono Radian 3R is a good option. 

Here are the narrowest car seats we reviewed:

What convertible car seats will fit 3 across?

The narrowest convertible car seats will fit 3 across. They are:

#1 Graco SlimFit3 LX  All-in-one Convertible Car Seat (16.7″)

#2 Diono Radian 3R All-in-one Convertible Car Seat (17″ for all in the Radian series)

#3 Clek Foonf All-in-one Convertible Car Seat (17″)

Which Graco car seat is the slimmest?

The Graco® SlimFit3™ LX 3-in-1 Car Seat features the slimmest design that fits 3 car seats across, saving space in your back seat without compromising on the safety you trust and the features you need.

How wide is the Graco SlimFit 3 LX?

At just 16.7 inches wide, the narrowness of this all-in-one convertible car seat makes installing three seats across possible in many vehicles, including small cars.

Does Britax make a slim convertible car seat?

Except for the Britax infant car seat, the Marathon is a great narrow convertible car seat from Britax, at just 18.5-inch wide. I

ts narrowness carries through to the entire seat, making it a good option for fitting multiple kids in the back seat.

It has an easy-to-use ClickTight system for a truly tight and proper installation, a steel frame, and SafeCell technology to keep your little one safe.