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Safety 1st EverSlim 4-in-1

The Safety 1st EverSlim 4-in-1 rear-faces up to 40 lb, forward-faces up to 65 lb, and has an expiration of 10 years, per Safety 1st. Four-mode Safety 1st seat with rear-facing, forward-facing and belt-positioning/backless booster modes, 5-position recline and a 10-position headrest and harness.

  • $229.99List price
  • 40 lbRear-facing to
  • 65 lbHarness to
  • 100 lbBooster to
See it on Safety 1st's site

When does it expire?

All all-in-one car seats

EverSlim 4-in-1: key facts

  • The Safety 1st EverSlim 4-in-1 rear-faces from 5 to 40 lb and 19 to 40 in tall; forward-faces with a harness from 30 to 65 lb and 34.4 to 49 in tall; works as a booster from 40 to 100 lb and 43.4 to 57 in tall, per Safety 1st.
  • Outgrown by height: "Rear-facing: the top of your child's head MUST be at least 1 in. (2.5 cm) below the top of the car seat's headrest. Forward-facing: the top of your child's ears MUST be below the top of the car seat's headrest. Booster: the top of your child's ears should never be above the top of the booster seat's headrest. Backless: the top of your child's ears should never be above the top of the vehicle seat back or vehicle headrest."
  • It installs with LATCH rear-facing, seat belt rear-facing, LATCH forward-facing + top tether, seat belt forward-facing + top tether or booster: vehicle lap/shoulder belt.
  • Safety 1st says it expires 10 years after the date of manufacture.
  • Safety 1st lists it as certified for aircraft ("This restraint is certified for aircraft use when used with the internal harness. / Booster Seat: This restraint is not certified for aircraft use, when used as a booster seat, because aircraft seats do not have shoulder belts.").

From Safety 1st's manual and published specs. Always follow the limits on your seat's labels.

How the EverSlim 4-in-1 stacks up

Against the 57 all-in-one car seats we track. The shaded band is where the middle half of them fall; the dot is this one.

Expiration10 years

The same as most all-in-one car seats (10 years).

This one
9 yearsmiddle 10 years12 years
Rear-facing limit40 lb11th highest rear-facing limit of 57

The same as most all-in-one car seats (40 lb).

This one
40 lbmiddle 40 lb50 lb
Price$229.9914th lowest price of 54

Within the typical range for all-in-one car seats ($229.99 to $399.99).

This one
$99middle $319.99$799.95

Flying with the EverSlim 4-in-1

Safety 1st's label: “This restraint is certified for aircraft use when used with the internal harness. / Booster Seat: This restraint is not certified for aircraft use, when used as a booster seat, because aircraft seats do not have shoulder belts.”

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

  • 5-position recline
  • Booster mode listed to 100 lb

Worth checking

  • Maker notes not all children will comfortably fit the full ranges

Where to buy the EverSlim 4-in-1

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

Safety 1st EverSlim 4-in-1
TypeAll-in-one
List price$229.99
Rear-facing weight5–40 lb
Rear-facing height19–40 in
Forward-facing weight30–65 lb
Forward-facing height34.4–49 in
Booster weight40–100 lb
Booster height43.4–57 in
Head ruleRear-facing: the top of your child's head MUST be at least 1 in. (2.5 cm) below the top of the car seat's headrest. Forward-facing: the top of your child's ears MUST be below the top of the car seat's headrest. Booster: the top of your child's ears should never be above the top of the booster seat's headrest. Backless: the top of your child's ears should never be above the top of the vehicle seat back or vehicle headrest.
Newborn insertHead pillow and body pillow, optional, rear-facing mode only; must be used together (EverSlim manual).
InstallationLATCH rear-facing, seat belt rear-facing, LATCH forward-facing + top tether, seat belt forward-facing + top tether, booster: vehicle lap/shoulder belt
Load legNo
Anti-rebound barNo
RotatesNo
Harness heights10
Recline positions5
Aircraft labelCertified for aircraft, per the maker
Expires after10 years

Compare the EverSlim 4-in-1 with

How each closest rival differs from the EverSlim 4-in-1, from the makers' specs.

Ask the meadow

EverSlim 4-in-1: questions answered

From Safety 1st's published specs, last checked 2026-11-06.

Does the Safety 1st EverSlim 4-in-1 rear-face longer than other all-in-one seats?

15 of the 70 all-in-one seats we track rear-face to a higher weight than its 40 lb. The highest is the Britax One4Life ClickTight All-in-One at 50 lb. NHTSA: stay rear-facing "until he or she reaches the top height or weight limit allowed by your car seat's manufacturer." (NHTSA)

Can you bring the Safety 1st EverSlim 4-in-1 on a plane?

Yes, Safety 1st 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.

Is it OK to buy a used EverSlim 4-in-1?

NHTSA publishes guidance on used car seats on its car seat page. Safety 1st 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 all-in-one 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.