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radian® 3QXT

The ultimate 3 across All-in-One car seat from birth to booster (4 – 120 lb / 1.8 – 54 kg). Featuring 4 stages of complete newborn protection and all new Diono Safe+™ engineering to provide the next generation in car seat safety.


Features Safe+™ newborn travel high wedge, Safe+™ newborn protection insert, Safe+™ 2-in-1 infant positioning liner and Safe+™ newborn harness pads to provide a custom fit from birth.
radian® 3QXT is subjected to a combination of the most rigorous crash tests; front, rear, and side impacts, and rollover test to make sure we have the safest seat possible.
With 5 ways to travel from birth to booster, the radian® 3QXT adapts as your child grows to offer a custom fit from birth up to 120 lb.

Designed and engineered with all new Diono Safe+™ protection. Now you can keep your child rear-facing for even longer up to 50 lb (approx. 4 years old).

Built with our famous radian® slim fit design, to fit 3 across in most vehicles without compromising child or passenger comfort.

4-50 lb / 1.8-22.7 kg

22-65 lb / 10-29.5 kg

Booster mode
40-120 lb / 18-54 kg

Seated torso height
7.5-16.5″ / 19-42 cm

Overall maximum height
up to 57″ / 144.8 cm

25.8 lb / 11.7 kg



Safe+™ newborn protection insert
Made from energy absorbing materials to support and protect. Super soft padding for extra newborn comfort. Simply remove as baby grows.

Safe+™ newborn travel high wedge
Creates near lie-flat travel position for newborns while reducing head slump and helping to keep airways open. Simply remove as baby grows.

Safe+™ 2-in-1 infant positioning liner
Gives extra infant comfort and toddler body support. Simply remove as baby grows.

Safe+™ newborn harness pads
Small sized newborn harness pads for added safety and comfort.

Key product features and benefits

Safe+™ steel anti-rebound bar
One click connection to the seat base. Reduces rebound rotation by 50% in the event of a collision. Also provides more legroom when rear facing.

Safe+™ side impact management pod

The pod is placed on the side of the car seat facing the door and is engineered to channel energy around the back of the car seat and away from the child in the event of a side impact.

Safe+™ steel core
All new upgraded steel core. Made from automotive grade high strength steel to shield and protect.

Safe+™ headrest
Engineered with the latest European Side Impact technology to improves child head containment in the event of any collision. Headreat height range increase by 22% from radian R series, from lowest to highest of the 12 positions.

Safe+™ side Impact protection

Featuring 8 layers of of interlocking EPS & EPP foam, high density plastic and steel reinforcement to create ultimate side impact protection without compromising 3 across fit.

what’s the difference? 

Additional 2 year warranty*

Receive an additional 2-years warranty on all car seats and strollers purchased from *T&C’s apply

FREE Shipping on orders over $200*

Diono proudly offers free shipping on orders over $200. *T&C’s apply

Join the Very Important Passenger Club

Unlock exclusive news, offers and discounts on all products.

1-2-1 Virtual Car Seat Fitting

Book a 1-2-1 virtual car seat fitting with a member of our car seat safety team


can the radian 3QXT fit 3-across in my car?

Most likely, yes, as long as you have 51” (129.6cm) in the back row from vehicle armrest to armrest. It may be necessary to install all three using the vehicle seat belt system.

can the harness straps be cleaned?

Yes, we recommend using a damp cloth with a solution of water and baking soda to wipe the straps clean. They cannot be saturated in any liquid, or they will need to be replaced. Replacement harness straps can be purchased on our website.

can I use the radian 3QXT from birth?

Yes, the weight limit on the QXT starts at 4lbs. The newborn must also meet a length requirement where the top of their shoulders reaches the lowest harness slot on the seat.

are the harness pads and buckle pads required on my seat?

Yes, they are required while your child is sitting in forward-facing. They are optional but recommended while sitting in rear-facing. The center buckle pad is required at all times.

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