The Complete List of Slim & Narrow Car Seats for 3-Across

Slim and ultra-narrow car seats are a hot trend right now. And while this new trend has been a godsend for many parents and caregivers looking to squeeze 3-across in their vehicle, it’s quite possible that the looming side-impact standard (FMVSS 213a), which will take effect on June 30, 2025, will force the discontinuation of some narrow harnessed car seats that aren’t able to comply with the stringent new requirements.

It’s also possible that manufacturers may be forced to redesign existing seats to beef up the headwings and/or add external side-impact “pods” to get the seat to pass this new federal standard.

We are concerned that these enhancements might have the unintended consequence of making slim and narrow car seats significantly wider. Time will tell, but the threat is real and we hope that we don’t lose the majority of our current selection of narrow car seats for the sake of progress in safety standards. .

With that said, we created this list as a resource for parents searching for a slim car seat. We included measurements, weight ranges and MSRP quotes to help you narrow down which seats might best suit your situation, and your budget.

(L to R): Revolve360 Slim, One4Life Slim, SlimFit3 LX, Radian RXT, Poplar, Scenera Next, Jive

Some of these narrow seats are “All-in-Ones” meaning that they can be used rear-facing, forward-facing and as a booster. Keep in mind that narrow car seats may not be sufficiently roomy to comfortably accommodate bigger, older children – especially for stockier kids with broad shoulders. If you buy an ultra-narrow All-in-One that is rated up to 100 lbs. (or more) in booster mode, just be realistic about your expectations.

A seat that is only 17″ wide may be perfect now but not be very comfortable down the line for an older kid who weighs 70+ lbs. There are always tradeoffs. While you should buy the seat that works for your situation now and in the near future, just be aware that the upper weight range for use in booster mode (if the seat that you’re considering can be used as a booster), may not be realistic.

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Slim Convertible & All-in-One Seats

Model Width Weight Range MSRP
Britax Poplar 17" RF 5-50 / FF 22-65 $299
Britax Poplar S with ARB 17" RF 5-50 / FF 22-65 $349
Britax One4Life Slim 17.5" RF 5-50 / FF 30-65 / BO 40-120 $399
Clek Fllo 17" RF 14-50 / FF 22-65 $449
Clek Foonf 17" RF 14-50 / FF 22-65 $559
Cosco Kids Scenera Next 17" RF 5-40 / FF 22-40 $59
Diono Radian 3R 17" RF 4-50 / FF 22-65 / BO 40-120 $199
Diono Radian 3RXT 17" RF 4-50 / FF 22-65 / BO 40-120 $299
Evenflo Revolve360 Slim 16.7" RF 4-50 / FF 22-65 $349
Graco EasyTurn 360 17" RF 5-40 / FF 26.5-65 $299
Graco SlimFit3 LX 16.7" RF 5-40 / FF 22-65 / BO 40-100 $279
Graco True3Fit LX with ARB 16.7" RF 5-40 / FF 22-65 / BO 40-100 $249
Safety 1st Jive 17.5" RF 5-40 / FF 22-65 $109
Safety 1st Ever Slim 17.5" RF 5-40 / FF 22-65 / BO 40-100 $199


Slim FF Harness Booster Combination Seats

Model Width Weight Range MSRP
Chicco MyFit Harness + Booster 17.5" FF 25-65 / BO 40-100 $219


Slim Highback Booster Seats

Model Width Weight Range MSRP
Diono Connect3 R (no Latch) 16.3" w/o cupholder 40-120 $109
Peg Perego Viaggio Flex 17.5" (adjustable) 40-120 $299

We hope this information was helpful in narrowing down which products meet your needs!

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A Comparison of Graco SlimFit3 LX & Original Graco SlimFit Models

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Doona vs. Evenflo Shyft DualRide: Battle of the Car Seat Stroller Combos