| Mode | Weight | Height |
|---|---|---|
| Rear-facing harness | 4–50 lb | 18–44 in |
| Forward-facing harness | 22–65 lb | 30–57 in |
| Belt-positioning booster | 40–120 lb | 40–57 in |
- Seat weight
- Not published
- Width
- Not published
- Usable life
- 10 years
- Aircraft
- Certified
Diono does not sell this seat on Amazon. See its own site for photos.
Diono Radian 3QX SafePlus All-in-One Convertible Car Seat
An all-in-one car seat with 3 modes: rear-facing harness 4 to 50 lb, 18 to 44 in; forward-facing harness 22 to 65 lb, 30 to 57 in; belt-positioning booster 40 to 120 lb, 40 to 57 in.
At a glance
- Fits children from 4 to 120 lb
- Up to 57 in tall
- 3 modes: rear-facing harness, forward-facing harness, belt-positioning booster
- 10-year usable life
- Certified for aircraft use
Not sold on Amazon
Diono lists this seat on its US site. Buy from Diono or an authorized retailer, and confirm the exact model number before you buy.
Who is the Radian 3QX SafePlus All-in-One Convertible Car Seat for?
The Radian 3QX SafePlus is an all-in-one car seat: rear-facing from 4 to 50 lb and 18 to 44 in, forward-facing with the harness from 22 to 65 lb and 30 to 57 in, then a booster from 40 to 120 lb. Diono lists it at 17 in wide, and it expires 10 years after purchase.
Reasons to consider it
- A 17 in width, with 51 in between door handles needed for 3 Diono car seats across
- Rear-facing to 50 lb or 44 in, with a detachable rear-facing base and an anti-rebound bar
- Aircraft use in harness mode, rear- or forward-facing
- A seat that folds and is held closed with its red carry strap
Things to weigh up
- Diono lists the seat at 31.3 lb
- LATCH is limited to 35 lb rear-facing and 40 lb forward-facing; the seat belt is used beyond that
- The 10-year life is split: 8 years in the 5-point harness and 2 years as a booster
- Booster mode needs a lap/shoulder belt, and it is not certified for aircraft in that mode
My take on the Radian 3QX SafePlus All-in-One Convertible Car Seat
The 3QX suits a family that wants one seat from birth to booster at a listed width of 17 in. Diono gives 51 in between door handles as the minimum for 3 Diono car seats across. The trade-off is bulk: Diono lists it at 31.3 lb, and rear-facing it uses 30 to 36 in between the back seat and the front seat back. The 3QXT shares the manual and limits but adds a Side Impact Management pod and newborn insert, and Diono lists it at 32 lb.
A research summary of Diono’s published specifications and manual, read . Not a hands-on test or a crash-safety rating.
Who the Radian 3QX SafePlus All-in-One Convertible Car Seat fits
This seat covers 3 stages, and a child has to meet every limit of the stage they are in. Diono gives it a 10-year life from the date of manufacture, so check the date label before using a hand-me-down.
- Rear-facing harness4 to 50 lb · 18 to 44 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 harness22 to 65 lb · 30 to 57 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.
- Belt-positioning booster40 to 120 lb · 40 to 57 in
- The seat raises the child so the vehicle’s own lap and shoulder belt sits on the hips and across the shoulder. The child has to sit properly for the whole ride.
What are the Radian 3QX SafePlus All-in-One Convertible Car Seat weight, height and age limits?
| Mode | Child weight | Child height | Minimum age | Conditions |
|---|---|---|---|---|
| Rear-facing harness | 4 to 50 lb | 18 to 44 in | Not published | — |
| Forward-facing harness | 22 to 65 lb | 30 to 57 in | Not published | 22-30 lb must use the middle buckle slot |
| Belt-positioning booster | 40 to 120 lb | 40 to 57 in | Not published | — |
A child must meet every limit for the mode they use. The labels on your seat and its manual are the final word.
Radian 3QX SafePlus All-in-One Convertible Car Seat specifications
- Seat weight
- Not published
- Width
- Not published
- Usable life
- 10 yearsTen years from date of purchase (8 years in 5-point harness, 2 years in booster)
- Aircraft use
- Certified for aircraft (see manual for which modes)
Will it fit your car?
Diono does not publish a width for this seat, so measure your back seat and compare it with the seat in a store before buying.
- 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 to know before you live with it
Rear-facing installation
Children under 22 lb or under one year old must ride rear-facing. Diono recommends attaching the detachable rear-facing base and the anti-rebound bar for rear-facing installs. With a flat seat bight, the base feet tuck into the bight; with an elevated bight, they sit flat and should not be pushed in, since that changes the recline. The blue level line on the label should be level with the ground. LATCH is allowed up to 35 lb; from 35 to 50 lb, reinstall with the seat belt, locked in ALR mode. The harness goes at or below the shoulders, with the head 1.5 in below the top of the shell.
Forward-facing, SafeStop and the adjustable bottom
Forward-facing with the harness runs from 22 to 65 lb and 30 to 57 in. From 22 to 30 lb the buckle must use the middle slot, and above 30 lb the forward-most slot. The SafeStop attaches to the harness for children from 22 to 40 lb and comes off at 40 lb. Lower the adjustable bottom for a child over 25 lb. LATCH is allowed to 40 lb, then the seat belt to 65 lb. The top tether is recommended in the US and required in Canada; with a lap-only belt and no tether anchor, the manual requires the 5th harness slot and the lap belt cushion.
Booster mode
Booster mode covers 40 to 120 lb and 40 to 57 in, after the 5-point harness is removed. The child's shoulders must be at or above the 4th harness slot. Only the vehicle lap/shoulder belt may be used: never a lap belt alone, the detachable base, or the adjustable bottom lowered. The bottom of the headrest should be even with the child's jaw. The shoulder belt runs through the upper guide, and the manual says to check before each ride that the belt retracts properly; if it does not, choose another seating position or stay in harness mode while the child still fits.
Cover, cleaning and folding
Removing the cover means taking out the harness, unclipping the headrest cover, unfastening snaps under the headrest, pulling the fabric out of the shell channel and freeing four plastic tabs under the front. Take the memory foam out of the seat pad and the wedge out of the infant support first, because neither is washed. Fabrics are machine or hand washed in cold water on a gentle cycle with mild detergent and dried flat in the shade, with no bleach, ironing or dry cleaning. To fold the seat, pull the red release levers and secure it with the red carry strap.
Is the Radian 3QX SafePlus All-in-One Convertible Car Seat recalled?
- 17C003000: does not cover this model. The Part 573 report for campaign 17C003000 lists six models only: Radian R100 (model no. 16600 or 16000), Radian R120 (16800 or 16000), Radian RXT (16900 or 16000), Olympia (30100), Pacifica (30400 or 300000) and Rainier (30300 or 300000), built between November 25, 2013 and September 5, 2017. The Radian 3QX is a separately named Radian 3 series seat and is not among the listed models. Campaign source (read ).
Each campaign naming this family was read against this model’s numbers and build dates, and none covers it. Still check your seat’s model number and date of manufacture before use, especially on a used seat.
Radian 3QX SafePlus All-in-One Convertible Car Seat: common questions
How wide and heavy is the Radian 3QX?
Diono lists it at 28.5 in tall, 17 in wide and 16 in deep, with a seat weight of 31.3 lb. These are manufacturer figures, not my own measurements.
Can the Radian 3QX fit 3-across?
Diono gives 51 in of vehicle seat width between the door handles as the minimum to fit 3 Diono car seats across.
Diono: Radian 3QX SafePlus 3-across space (opens in a new tab)
How much front-to-back room does the 3QX need rear-facing?
Diono says a rear-facing 3QX uses 30 to 36 in between the vehicle's back seat and the back of the front seat, depending on seat shape and contour.
Diono: Radian 3QX SafePlus rear-facing room (opens in a new tab)
Can I use the Radian 3QX on a plane?
The manual says it is certified for aircraft only in harness mode, installed with the lap belt rear- or forward-facing. It is not certified in booster mode, because aircraft seats have no shoulder belt.
Diono Radian 3Q SafePlus Series manual (PDF) (opens in a new tab)
When does the Radian 3QX expire?
The manual says ten years from the date of purchase, with 8 years in the 5-point harness and 2 years in booster mode.
Diono Radian 3Q SafePlus Series manual (PDF) (opens in a new tab)
How is the Radian 3QXT different from the 3QX?
Diono lists the 3QXT at 32 lb with the same 17 in width. It adds a newborn insert and a Side Impact Management pod to the 3QX's adjustable headrest, infant insert and anti-rebound bar.
Diono Radian 3QXT SafePlus support page (opens in a new tab)
Answers refer to the model and manual version on this page. Check the instructions supplied with your seat.
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.
- 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 Diono so you hear about the next one.
Sources
- Diono US product page
- Radian3Q_SafePlus_Series_English_Manual.pdf
- diono.zendesk.com/hc/en-us/articles/17137894364819-Radian-3QX-SafePlus-Radian-3QX-Manual
- Diono Radian 3Q SafePlus Series manual (PDF)
- Diono Radian 3QX SafePlus support page
- Diono: Radian 3QX SafePlus dimensions
- Diono: Radian 3QX SafePlus 3-across space
- Diono: Radian 3QX SafePlus rear-facing room
- Diono Radian 3QXT SafePlus support page
- NHTSA car seat guidance
Other Diono convertible car seats
| Model | Top child weight | Seat weight | Width | Usable life |
|---|---|---|---|---|
| Radian 3QX SafePlus All-in-One Convertible Car Seat (this seat) | 120 lb | — | — | 10 years |
| Radian 3QXT SafePlus All-in-One Convertible Car Seat | 120 lb | — | — | 10 years |
| Radian 3QXT FirstClass SafePlus (Radian 3QXT+) All-in-One Convertible Car Seat | 120 lb | — | — | 10 years |
| Radian 3R SafePlus All-in-One Convertible Car Seat | 120 lb | — | — | 10 years |
| Radian 3RXT SafePlus All-in-One Convertible Car Seat | 120 lb | — | — | 10 years |
| Radian 3RXT SafePlus Max All-in-One Convertible Car Seat | 120 lb | — | — | 10 years |
| Radian 3R All-in-One Convertible Car Seat | 120 lb | — | — | 10 years |
| Radian 3RX All-in-One Convertible Car Seat | 120 lb | — | — | 10 years |
| Radian 3RXT All-in-One Convertible Car Seat | 120 lb | — | — | 10 years |