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Britax Poplar S

The Britax Poplar S rear-faces up to 50 lb, forward-faces up to 65 lb, and is 17 in wide, per Britax. The Poplar with extras: a ReboundReduce stability bar, upper-body support pillow and contrast stitching. Same slim 17-inch frame.

  • $399.99List price
  • 50 lbRear-facing to
  • 65 lbHarness to
  • 28 lbSeat weight
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When does it expire?

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All convertible car seats

Poplar S: key facts

  • The Britax Poplar S rear-faces from up to 50 lb and 18 to 49 in tall; forward-faces with a harness from up to 65 lb and 35 to 49 in tall, per Britax.
  • Outgrown by height: "Rear-facing: when the top of the child's head is at least 1" (2.5 cm) below the top of the head restraint. Forward-facing: when the top of the ears are below the top of the head restraint."
  • It installs with seat belt (ClickTight).
  • Britax says it expires 10 years after the date of manufacture.
  • Britax lists it as certified for aircraft ("This restraint is certified for motor vehicles and aircraft use.").
  • It's 17 in wide at the widest point and weighs 28 lb.

From Britax's manual and published specs. Always follow the limits on your seat's labels.

How the Poplar S stacks up

Against the 39 convertible car seats we track. The shaded band is where the middle half of them fall; the dot is this one.

Expiration10 years

Within the typical range for convertible car seats (9 years to 10 years).

This one
7 yearsmiddle 10 years10 years
Rear-facing limit50 lb2nd highest rear-facing limit of 38

Within the typical range for convertible car seats (40 lb to 50 lb).

This one
35 lbmiddle 40 lb65 lb
Forward-facing limit65 lbHighest forward-facing limit of 38 convertible car seats

The same as most convertible car seats (65 lb).

This one
40 lbmiddle 65 lb65 lb
Width17 in5th narrowest of 28

Within the typical range for convertible car seats (17 in to 18.9 in).

This one
14.5 inmiddle 17.8 in23.5 in
Weight28 lb20th lightest of 25

Above the typical range for convertible car seats (21.6 lb to 27.9 lb).

This one
8 lbmiddle 25.2 lb31.3 lb
Price$399.9919th lowest price of 37

Within the typical range for convertible car seats ($129.99 to $499.99).

This one
$59.99middle $399.99$990

What sets the Poplar S apart

Measured against the 39 convertible car seats we compare, from each maker's published specs.

  • 5th narrowestof the 28 convertible car seats with it published: 17 in
  • Weight: 28 lbabove the middle half of the 25 convertible car seats that publish it (21.6 lb to 27.9 lb)

Next to its closest matches

  • Britax Galaxy360 SlimNext to it, the Poplar S is $30 less; no rotates (the Galaxy360 Slim has it); has aircraft label (the Galaxy360 Slim doesn't).
  • Britax PoplarNext to it, the Poplar S is 0.8 lb heavier; $50 more; has anti-rebound bar (the Poplar doesn't).
  • Evenflo Gold Revolve360 SlimNext to it, the Poplar S is 0.1 in wider; 0.2 lb lighter; $50 less; has anti-rebound bar (the Gold Revolve360 Slim doesn't); no rotates (the Gold Revolve360 Slim has it).

Flying with the Poplar S

Britax's label: “This restraint is certified for motor vehicles and aircraft use.” It is 17 in wide at its widest point.

What airlines say about car seats:

  • American: “Each ticketed customer is allowed 1 stroller and 1 car seat to be checked free of charge” “If an unoccupied, adjoining seat is not available, the gate agent will check the safety seat to your final destination.” Source
  • Alaska: “We will transport your child's car seat and stroller free of charge as checked baggage.” Source
  • JetBlue: “Checking a child safety seat will not count towards your checked baggage allowance and there is no fee assessed” Source
  • Spirit: “One (1) car seat will be accepted per child as checked baggage at no charge.” Source
  • Frontier: “strollers and car seats can be checked for free.” Source
  • Allegiant: “There is no charge for checking or gate checking one car seat per fare-paying passenger.” Source
  • Breeze: “Child seats may be carried on board the aircraft if a seat has been purchased for the Infant or Child” Source

Quoted from each airline's page as of 2026-11-02.

Listed features

  • Slim 17-inch width
  • Includes rebound-reducing stability bar
  • 10-year life

Worth checking

  • Costs more than the Poplar for mostly comfort and bar extras

Where to buy the Poplar S

Prices and availability change. We may earn a commission from some links.

good to know
  • Check for recalls: Search the agency's recall list with the model number and date code from the label: NHTSA recall search.
  • Car seat use and installation: see NHTSA's car seat page, which also lists free car seat inspection by certified technicians. Check the label and the maker's instructions, and ask your pediatrician about your child.

Full specs

Britax Poplar S
TypeConvertible
List price$399.99
Rear-facing weightUp to 50 lb
Rear-facing height18–49 in
Forward-facing weightUp to 65 lb
Forward-facing height35–49 in
Seat weight28 lb
Width17 in
Head ruleRear-facing: when the top of the child's head is at least 1" (2.5 cm) below the top of the head restraint. Forward-facing: when the top of the ears are below the top of the head restraint.
Newborn insertInfant inserts (optional, two per product page): DO NOT use any infant inserts with children weighing over 20 lbs (9.1 kg) rear-facing; not forward-facing.
Installationseat belt (ClickTight)
Load legNo
Anti-rebound barYes
RotatesNo
Harness heights14
Recline positions6
Aircraft labelCertified for aircraft, per the maker
No added flame retardantsYes
Expires after10 years

Compare the Poplar S with

How each closest rival differs from the Poplar S, from the makers' specs.

Ask the meadow

Poplar S: questions answered

From Britax's published specs, last checked 2026-11-06.

Does the Britax Poplar S rear-face longer than other convertible seats?

1 of the 50 convertible seats we track rear-face to a higher weight than its 50 lb. The highest is the Axkid One 3 at 65 lb. NHTSA: stay rear-facing "until he or she reaches the top height or weight limit allowed by your car seat's manufacturer." (NHTSA)

Will the Britax Poplar S fit three across or in a small car?

It's narrower than 68% of the convertible seats we track, at 17 in. The narrowest is the WAYB Pico at 14.5 in. Fit depends on your vehicle; check each seat's manual and your vehicle manual. Car seat use and installation: see NHTSA's car seat page, which also lists free car seat inspection by certified technicians. Check the label and the maker's instructions, and ask your pediatrician about your child.

Can you bring the Britax Poplar S on a plane?

Yes, Britax lists it as certified for aircraft; look for the red-lettered label that says so. The FAA asks that a car seat go in a window seat so it doesn't block the aisle, and the crew will look for that label. It weighs 28 lb to carry through the airport.

Poplar S or Galaxy360 Slim: what's different?

By the makers' specs, the Galaxy360 Slim has a rotating seat; the Poplar S lists for $30 less. See every spec side by side.

Is it OK to buy a used Poplar S?

NHTSA publishes guidance on used car seats on its car seat page. Britax lists a lifespan of 10 years from manufacture for this model. Check the label and the maker's instructions, and ask your pediatrician about your child.

Still wondering? Write to us at hello@cribpicks.com and we'll look it up.

More convertible car seats

Where these specs come from

Last checked 2026-11-06. Spot something wrong? Tell us. Read our editorial and safety policy and corrections.