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Diono Radian 3QX

The Diono Radian 3QX rear-faces up to 50 lb, forward-faces up to 65 lb, and is 17 in wide, per Diono. Diono's slim 17 in all-in-one that rear-faces to 50 lb and carries a child through high-back booster to 120 lb.

DiscontinuedNo longer made or sold new. Specs are kept for comparing generations.

  • $399.99List price
  • 50 lbRear-facing to
  • 65 lbHarness to
  • 120 lbBooster to
See it on Diono's site

When does it expire?

All all-in-one car seats

Radian 3QX: key facts

  • The Diono Radian 3QX rear-faces from 4 to 50 lb and 18 to 44 in tall; forward-faces with a harness from 22 to 65 lb and 30 to 57 in tall; works as a booster from 40 to 120 lb and 40 to 57 in tall, per Diono.
  • Outgrown by height: "Rear-facing: Top of head must be 1.5 in. (3.8 cm) below the top of the car seat shell. Forward-facing: Top of child's ears MUST be below top of car seat shell."
  • It installs with LATCH or seat belt.
  • Diono says it expires 10 years after the date of manufacture.
  • Diono lists it as certified for aircraft ("This child restraint is certified for use in aircraft only when in harness mode.").
  • It's 17 in wide at the widest point and weighs 29.6 lb.

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

How the Radian 3QX stacks up

Against the 58 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 limit50 lbHighest rear-facing limit of 58 all-in-one car seats

Above the 40 lb most all-in-one car seats list.

This one
40 lbmiddle 40 lb50 lb
Width17 in4th narrowest of 34

Below the typical range for all-in-one car seats (18 in to 19.5 in).

This one
16.7 inmiddle 19 in21.5 in
Weight29.6 lb28th lightest of 36

Above the typical range for all-in-one car seats (20 lb to 29.3 lb).

This one
12.2 lbmiddle 25.5 lb35 lb
Price$399.9939th lowest price of 55

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 Radian 3QX

Diono's label: “This child restraint is certified for use in aircraft only when in harness mode.” 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

  • 17 in wide for tight back seats
  • Rear-facing to 50 lb
  • Steel core frame

Worth checking

  • Heavy at 29.6 lb
  • Needs significant front-to-back room rear-facing
  • Fabrics contain flame retardants

Where to buy the Radian 3QX

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

good to know
  • Discontinued. You may still find it used or on clearance.
  • 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

Diono Radian 3QX
TypeAll-in-one
List price$399.99
Rear-facing weight4–50 lb
Rear-facing height18–44 in
Forward-facing weight22–65 lb
Forward-facing height30–57 in
Booster weight40–120 lb
Booster height40–57 in
Seat weight29.6 lb
Width17 in
Head ruleRear-facing: Top of head must be 1.5 in. (3.8 cm) below the top of the car seat shell. Forward-facing: Top of child's ears MUST be below top of car seat shell.
InstallationLATCH, seat belt
Load legNo
Anti-rebound barYes
RotatesNo
Aircraft labelCertified for aircraft, per the maker
No added flame retardantsNo
Expires after10 years

Compare the Radian 3QX with

How each closest rival differs from the Radian 3QX, from the makers' specs.

Ask the meadow

Radian 3QX: questions answered

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

Does the Diono Radian 3QX rear-face longer than other all-in-one seats?

Yes. Its 50 lb rear-facing limit is the highest of the 70 all-in-one seats we track, tied with 14.

Will the Diono Radian 3QX fit three across or in a small car?

It's narrower than 86% of the all-in-one seats we track, at 17 in. The narrowest is the Chicco Fit3x ClearTex Ultra-Slim All-in-One at 16.7 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 Diono Radian 3QX on a plane?

Yes, Diono 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 29.6 lb to carry through the airport.

Radian 3QX or One4Life ClickTight All-in-One: what's different?

By the makers' specs, the Radian 3QX has an anti-rebound bar; the One4Life ClickTight All-in-One has no added flame retardants (maker's claim); the Radian 3QX lists for $40 less. See every spec side by side.

Is it OK to buy a used Radian 3QX?

NHTSA publishes guidance on used car seats on its car seat page. Diono 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.