Chicco Fit3X

If you’ve been searching for a narrow car seat, you’ve probably come across the Graco SlimFit3 LX. It’s been one of our go-to recommendations for tight spaces and three-across setups for a long time.

But now? Thee Chicco Fit3X gives it some serious competition.

If you’re already comparing the two, you’re probably wondering, “What’s the difference between the Chicco Fit3X and the Graco SlimFit3 LX?” Aside from their confusingly similar names, they’re extremely tough competitors, with a few key differences that might make one a better fit for your family.

But this isn’t strictly a comparison. I’m going to focus on the Fit3X here and what makes this 16.7-inch-wide seat such an interesting option, especially if you’re trying to fit three across. You can read my full Graco SlimFit3 LX review here if you want to compare the two.

I’m Carly, a CPST and mom of three. I own a lot of car seats, and most of them have been purchased because they’re problem solvers. Sometimes that means a seat does one specific thing I need it to do, and sometimes that means it does a lot of different things well. The Chicco Fit3X is somehow both.

Consider the Chicco Fit3X if:

• You’re trying to achieve three across. At just 16.7 inches wide, the Fit3X is designed with three-across setups in mind.
• You want a versatile secondary seat. It can be used rear-facing, forward-facing, and as a high-back booster.‍
• You need extra room in a forward-facing harness. With an 18-inch top harness height and 54-inch standing height limit, the Fit3X can give valuable extra harness time to kids who are taller, longer-torsoed, or have another reason to need a harnessed seat past the typical age and size of booster readiness.

Keep looking if:

• You want a seat with a built-in tensioner. The Fit3X has built-in lock-offs, but they’re passive and don’t help tighten the seat belt for you.
• You need a super compact rear-facing seat. The Fit3X is narrow side-to-side, but it’s about average front-to-back and takes up significant space when deeply reclined for a newborn.
• Your vehicle has non-removable, protruding headrests. The Fit3X doesn’t allow a gap between the vehicle seat and car seat caused by the headrest, although its shape can bypass some fixed headrests.

Chicco Fit3X Height and Weight Limits

The Chicco Fit3X is a 3-in-1 car seat that can be used rear-facing, forward-facing, and as a high-back booster.

Here are the key limits Carly calls out in this review:

• Rear-facing weight limit: 40 pounds
• Rear-facing height limit: 43 inches
• Forward-facing standing height limit: 54 inches
• Top harness height: 18 inches

The 40-pound and 43-inch rear-facing limits are on the lower end compared to some seats, but they should still allow many children to rear-face until around age four. Where the Fit3X really stands out is forward-facing, with an above-average 18-inch top harness height and 54-inch standing height limit.

Chicco Fit3X Features

How Wide Is the Chicco Fit3X?

At just 16.7 inches wide, it really doesn’t get much narrower, though there are a couple of other seats on the market with the same overall width.

That narrow footprint is a big part of what makes the Fit3X such a strong contender for three-across setups. The lower-profile sides can also make it easier for kids to get in and out of the seat, especially when they’re in the "doing It themselves" phase...

Chicco Fit3X Fabric and Comfort

The Fit3X manages to have some pretty impressive features at the $229.99 price point. The ClearTex fabric is chemical flame retardant-free, and the seating area feels nice and plush.

It comes in two neutral colors, Black and Oat, plus Lupine, an almost-neutral but still unique purplish-gray.

Built-In Lock-Offs Can Give You More Flexibility for Three Across

If you’re installing the Chicco Fit3X with the vehicle seat belt, it has built-in lock-offs for both rear- and forward-facing installations.

ICYMI: A lock-off is essentially a part of the car seat that holds the vehicle seat belt in place once the seat is installed!

The Fit3X uses passive lock-offs, meaning they help secure the seat belt but don’t actually tighten it for you. You’ll still need to get the installation tight yourself, and threading the shoulder belt through the lock-off can be a little tricky.

One particularly helpful feature for three-across setups is that the lock-offs allow for a slightly off-center installation. That little bit of flexibility can be crucial when you’re trying to make three car seats or passengers fit safely across one row.

The Flex-Forward Buckle Makes Buckling Kids In Easier

Perhaps the most surprising and welcome feature on the Fit3X is the flex-forward buckle. This is something you typically only find on higher-priced car seats, and it’s honestly kind of a game-changer when you’re getting a child into the seat.

The buckle flips forward and stays out of the way while your child gets in, which means no more digging around underneath their bottom trying to find it when it’s time to buckle up.

The LATCH System Has Some Thoughtful Upgrades

The Fit3X LATCH system has a couple of unique and helpful features: a Mini Tether and Mini-Grip lower anchor connectors.

The smaller-than-standard tether fits more easily under vehicle headrests, and its design makes it easier to loosen than a standard adjuster. The Mini-Grip lower anchor connectors also include plastic elements that make them easier to attach and detach than typical J-hook-style connectors.

The Side Impact Bolsters Don’t Get in the Way of a Good Fit

Normally, a specific piece of a car seat wouldn’t get its own section, but there’s a lot to talk about here. Due to updated side impact standards, manufacturers have engineered their seats to manage forces in a few different ways. Some have bulked up the seat shell or added larger head wings, while others, like the Fit3X, use supports inside the seat to help manage movement of the child’s body.

In some seats, these required inserts can create fit issues, especially for kids approaching the upper end of the required weight range. I’m happy to report that the Fit3X bolsters are pretty unobtrusive by comparison. I tried both of my differently shaped 45-pound children in the seat with the insert, and neither had any issues with fit or comfort.

One important thing to remember: the bolsters are required for children up to 40 pounds. Once you remove them, label them and put them somewhere you’ll actually remember! Inserts have a way of disappearing, and you won’t be able to safely use the seat later for a smaller child, like a younger sibling, without them.

Lower Anchor Storage Might Be the Fit3X’s Achilles Heel

While the Mini-Grip lower anchor connectors themselves are an upgrade over standard J-hook connectors, the storage situation just might be the Achilles heel of the whole seat.

A few things make it frustrating:

• The storage compartment behind the seat padding is surprisingly small.
• There are some very tempting lower-anchor-storage-bar-looking parts on the outside of the shell that unfortunately cannot be used for storage.
• Moving the connectors to the correct belt path or back into storage has left me with a web of tangled harness straps, lower anchor strap, and side impact padding nearly every time.

The Mini-Grip design does redeem itself a little. The ergonomic plastic elements make the connectors much more pleasant to attach and detach than standard J-hook connectors.

The “Fit” in Fit3X: How It Fits Kids

A big part of the Fit3X’s versatility is right there in the name: who and where it fits. As a 3-in-1 car seat, it can be used rear-facing, forward-facing, and in high-back booster mode.

The entire premise of this seat is that it can be used in three modes and three across, and in my experience, it stands a good chance of fulfilling that goal in a lot of situations.

The Fit3X Can Work Well Rear-Facing, Even From Birth

Although I haven’t had a chance to test the Fit3X with a real newborn, it appears to be an excellent contender if you’re hoping to skip the infant car seat. The fit on my newborn-sized doll was excellent.

Except in vehicles with very sloped seats, the Fit3X can provide the deep recline needed for a newborn, which isn’t always the case with convertible and all-in-one car seats.

The tradeoff is space. Achieving that deep recline takes up significant room front-to-back, so using the Fit3X this way will only work in larger vehicles.

The Fit3X Can Give Taller Kids More Time in a Harness

Forward-facing mode is where the Fit3X really stands out. Compared to what Carly typically sees in harnessed seats, you get:

• 18-inch top harness height, compared to a more common 17 inches
• 54-inch standing height limit, compared to the usual 49 inches

That extra room can give valuable time in the harness for kids who are taller, have longer torsos, or have another specific reason to need a harnessed seat beyond the typical age and size of booster readiness.

The full 54-inch height limit probably won’t be realistic for most kids, since the harness will almost certainly fall below their shoulders before then. But that extra buffer beyond 49 inches could still be really beneficial for some children.

The Fit3X Is a Strong Option if You Need a Narrow Booster

If slim is what you need in a booster, the Fit3X just might be your answer. It’s not an especially long-lasting booster, but it may get you through those first few booster years when the high-back feature may be most important.

There are a few things I especially like about it in booster mode:

• The low-profile sides and lack of armrests make it relatively easy for kids to access the vehicle buckle.
• Its narrow design makes it a strong contender when space is limited.
• At $229.99, the price may make sense even if you only plan to use the Fit3X as a booster, especially compared to our frequently recommended narrow booster, the Peg Perego Viaggio Flex 120.

Switching between harness and booster modes is relatively easy, but I wouldn’t necessarily choose it if you plan to switch back and forth regularly for different children. Depending on the child using harness mode, you may have to deal with the side impact bolsters, and as we already covered, the lower anchors can be a bit of a situation.

Chicco Fit3X Vehicle Fit: Front-to-Back Space, Buckles + Headrests

The Fit3X is just about average when it comes to front-to-back space. Compared to its closest competitor, the Graco SlimFit3 LX, the two are very similar, although the Fit3X is just a smidge larger.

Where its narrow design can really come in handy is in vehicles with rigid or recessed seat belt buckles. Wider car seats can be difficult or even impossible to install with the seat belt in these vehicles because the base of the car seat may end up sitting on top of the buckle.

One other thing to watch for is your vehicle headrest. The Fit3X does not allow a gap between the vehicle seat and car seat caused by the headrest, although the shape of the Fit3X can bypass some fixed headrests.

Is the Chicco Fit3X Worth It?

If you need a slim car seat, the Fit3X is an obvious contender. At just 16.7 inches wide, it’s a strong option for three-across setups, but that’s far from the only reason I like it.

It also gives you a surprisingly impressive list of features for the price, including:

• Three modes of use: rear-facing, forward-facing, and high-back booster
• Longer-than-average forward-facing harness height
• Built-in lock-offs that can give you more flexibility in three-across setups
• A flex-forward buckle that makes loading kids easier
• A narrow booster mode that’s relatively easy for kids to buckle

It may not be perfect, but no car seat is. For families who need a slim, versatile seat that can solve several different problems, the Fit3X is a very welcome addition to the current car seat lineup.

Chicco Fit3X FAQs

How Wide Is the Chicco Fit3X?

The Chicco Fit3X is 16.7 inches wide. There are only a couple of other seats on the market with the same overall width.

Can the Chicco Fit3X Fit Three Across?

The Fit3X is designed to be used in three modes and three across. In my experience, it stands a good chance of fulfilling that goal in many situations.

What Are the Chicco Fit3X Rear-Facing Limits?

The Fit3X can be used rear-facing up to 40 pounds or 43 inches. While those limits are on the lower end of the range, they should still allow many children to rear-face until around age four.

Can You Use the Chicco Fit3X With a Newborn?

I haven’t tested the Fit3X with a real newborn, but the fit on my newborn-sized doll was excellent. It appears to be an excellent contender if you’re hoping to skip an infant seat, although achieving the deep recline needed for a newborn takes up significant space.

How Long Does the Chicco Fit3X Last Forward-Facing?

The Fit3X has an 18-inch top harness height and a 54-inch standing height limit. This can provide valuable extra harness time for taller or longer-torsoed children, although the full 54-inch standing height limit probably won’t be realistic for most kids.

Does the Chicco Fit3X Convert to a Booster?

Yes. The Fit3X converts to a high-back booster. It isn’t especially long-lasting in booster mode, but the low-profile sides and lack of armrests make the vehicle buckle relatively easy to access.