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Britax Poplar Convertible Car Seat

A convertible car seat with 2 modes: rear-facing harness 5 to 50 lb, 18 to 49 in; forward-facing harness 30 to 65 lb, 35 to 49 in.

At a glance

Fits children from 5 to 65 lb
Up to 49 in tall
2 modes: rear-facing harness, forward-facing harness
Seat weighs 27.2 lb
17 in wide
10-year usable life
Certified for aircraft use

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Britax product page Manual

Specifications checked against Britax’s US site and manual on September 17, 2026. Not hands-on tested. How I research

Who the Poplar Convertible Car Seat fits

This seat covers 2 stages, and a child has to meet every limit of the stage they are in. Britax gives it a 10-year life from the date of manufacture, so check the date label before using a hand-me-down.

Rear-facing harness5 to 50 lb · 18 to 49 in: The child faces the back of the car, which keeps the head, neck and spine supported in a frontal crash. Keep this mode as long as the child fits it.
Forward-facing harness30 to 65 lb · 35 to 49 in: The child faces forward in the seat’s own harness. Use the top tether every time, and stay in the harness until the child outgrows it.

A toddler standing next to an empty convertible car seat

What are the Poplar Convertible Car Seat weight, height and age limits?

Britax Poplar Convertible Car Seat limits by mode
Mode	Child weight	Child height	Minimum age	Conditions
Rear-facing harness	5 to 50 lb	18 to 49 in	Not published	Lower anchor installation limited to 35 lb (manual)
Forward-facing harness	30 to 65 lb	35 to 49 in	Not published	Lower anchor installation limited to 35 lb (manual)

A child must meet every limit for the mode they use. The labels on your seat and its manual are the final word.

Poplar Convertible Car Seat specifications

Seat weight: 27.2 lb
Width: 17 in
Usable life: 10 years
Aircraft use: Certified for aircraft (see manual for which modes)
Dimensions as stated: 20.5" x 17" x 23.5"
Harness positions: 14
Recline positions: 6
Buckle strap depths: 4, 7 in
Seat area depth: 11 in
Seat area width: 12 in
Shoulder width: 14 in
Harness slot heights: 8, 8.7, 9.4, 10.1, 10.8, 11.5, 12.2, 12.9, 13.6, 14.3, 15, 15.7, 16.4, 17 in

How the Poplar Convertible Car Seat installs

Belt lock-off: ClickTight installation. A lock-off clamps the vehicle belt so you do not have to switch the belt's retractor into its locked mode.
Recline: 6 recline positions. The recline angle is what keeps a young baby’s airway open, so set it before tightening the install.
Harness: 14-position no-rethread harness and headrest. Check the harness height at each growth spurt: at or below the shoulders rear-facing, at or above them forward-facing.

Every install is a fit between one seat and one vehicle. Read both manuals, and use a free inspection station if anything is unclear.

An empty car seat installed on a back seat, seen through an open car door

Will it fit your car?

At 17 in at its widest, this seat is one of the narrower ones in its class and is a candidate for three across in many mid-size cars. It weighs 27.2 lb, which matters if you will move it between cars or carry it through an airport.

Check your vehicle manual for lower anchor positions and any head-restraint rules.
Rear-facing seats need front-seat room: try the install behind the driver before you commit.
Certified for aircraft use, so it can travel as a seat rather than checked baggage.

What features does the Poplar Convertible Car Seat have?

ClickTight installation
14-position no-rethread harness and headrest
6 recline positions
V-shaped tether
SafeCell technology
Carbon steel frame

Colors listed in the US

Stone Onyx, Glacier Graphite.

Is the Poplar Convertible Car Seat recalled?

No campaign in the current NHTSA child-restraint data names this model family, and I have not run a separate review for it. Check your seat’s model number and date of manufacture before use.

NHTSA recall search · Recent car seat recalls

Before you buy

Weigh and measure your child. The limits above are the manufacturer’s, and a child has to meet all of them for the mode they will use.
Confirm the exact version. Colors, retail exclusives and model numbers change limits more often than you would expect; Britax lists 2 colors of this seat.
Read the manual before you buy, not after. It is linked above and holds the fit rules, the install methods and the expiry.
Check recalls by model number and date of manufacture, and register the seat with Britax so you hear about the next one.

Sources

Other Britax convertible car seats

Model	Top child weight	Seat weight	Width	Usable life
Poplar Convertible Car Seat (this seat)	65 lb	27.2 lb	17 in	10 years
Poplar S Convertible Car Seat	65 lb	28 lb	17 in	10 years
One4Life ClickTight All-in-One Car Seat	120 lb	30 lb	19.5 in	10 years
One4Life Slim All-in-One Car Seat	120 lb	28 lb	—	10 years