| 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 3R All-in-One Convertible Car Seat
An all-in-one car seat with 3 modes: rear-facing harness 5 to 50 lb, 18 to 44 in; forward-facing harness 26.5 to 65 lb, 30 to 57 in; belt-positioning booster 40 to 120 lb, 40 to 57 in.
At a glance
- Fits children from 5 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 3R All-in-One Convertible Car Seat for?
The Radian 3R is Diono's folding all-in-one car seat. Its 2026 manual lists rear-facing from 5 to 50 lb and 18 to 44 in, a forward-facing harness from 26.5 to 65 lb and 30 to 57 in, and booster mode from 40 to 120 lb. It expires ten years from purchase: 8 years in harness and 2 in booster.
Reasons to consider it
- Rear-facing up to 50 lb or 44 in
- LATCH, lap/shoulder belt or lap belt installs in both harness modes
- Harness modes certified for aircraft
- A 17 in width; Diono says three Radian models need at least 51 in between door handles
Things to weigh up
- Minimum rear-facing weight is 5 lb
- Expiry is split: 8 years in harness, 2 years in booster
- The rear-facing top tether extension strap is sold separately
- Infant insert and cup holders come only with select models
My take on the Radian 3R All-in-One Convertible Car Seat
It suits a family that wants one all-in-one seat with long rear-facing limits and a simple feature set. The trade-off is that its manual describes no adjustable headrest, and its expiry is split into 8 years of harness use and 2 of booster use. Diono lists it at 17 in wide and 25.9 lb. The Radian 3R SafePlus starts rear-facing at 4 lb instead of 5 lb and adds a lever-adjusted headrest, with the same forward-facing and booster limits.
A research summary of Diono’s published specifications and manual, read . Not a hands-on test or a crash-safety rating.
Who the Radian 3R 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 harness5 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 harness26.5 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 3R All-in-One Convertible Car Seat weight, height and age limits?
| Mode | Child weight | Child height | Minimum age | Conditions |
|---|---|---|---|---|
| Rear-facing harness | 5 to 50 lb | 18 to 44 in | Not published | — |
| Forward-facing harness | 26.5 to 65 lb | 30 to 57 in | Not published | 26.5-30 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 3R 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 install and the base
Rear-facing covers 5 to 50 lb and 18 to 44 in. LATCH is limited to 5 to 35 lb, and the vehicle belt covers 5 to 50 lb. Diono recommends the detachable rear-facing base, used only rear-facing. Its feet tuck into a normal seat bight, but with an elevated bight they sit flat on the cushion and must not be pushed in. The manual's recline level indicator section is marked for Canada only. Test at the rear-facing belt path for less than 1 in of movement. Diono recommends rear-facing until two years of age or until the seat's rear-facing limit, and under 26.5 lb and under one year must be rear-facing.
Forward-facing and booster use
Forward-facing is 26.5 to 65 lb and 30 to 57 in. LATCH is allowed to 40 lb, then the lap/shoulder belt to 65 lb. Children from 26.5 to 30 lb use the middle buckle slot and those above 30 lb the forward-most slot. The top of the seat must be supported by the vehicle head support or seat back, and no more than 20% of the base may overhang the cushion. With only a lap belt and no tether, use the 5th harness slot and the lap belt cushion. Booster mode, 40 to 120 lb, uses only the lap/shoulder belt with the harness removed, and the shoulders must be at or above the 4th slot.
Cover removal and washing
To take the cover off, remove the harness, undo three tabs on the back, four snaps on the lower back of the shell, four snaps on the front beside the lower belt guide and two tabs underneath. Reverse the steps to refit it. Remove the memory foam before washing and do not wash the foam. The cover, harness pads and buckle pad go in the machine cold on a gentle cycle and dry flat away from direct sun, with no bleach, iron or dry cleaning. Spot clean the harness and plastics, and do not soak or hose the frame, since internal parts could rust.
Is the Radian 3R 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 3R 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 3R All-in-One Convertible Car Seat: common questions
What are the Radian 3R weight and height limits?
Rear-facing is 5 to 50 lb and 18 to 44 in, the forward-facing harness is 26.5 to 65 lb and 30 to 57 in, and booster mode is 40 to 120 lb and 40 to 57 in. The seat is for children 57 in or less.
When does the Radian 3R expire?
The manual says ten years from the date of purchase, made up of 8 years in the 5-point harness and 2 years in booster mode.
Can the Radian 3R be used on an airplane?
Yes in harness mode. The manual says to ask the flight attendant for a seat belt extender and follow the lap belt instructions for rear-facing or forward-facing. It is not certified for aircraft in booster mode.
How much room does the Radian 3R need rear-facing?
Diono says a rear-facing Radian 3R uses 30 to 36 inches between the vehicle's back seat and the front seat back, depending on the seat shape and contour.
Diono support: Radian 3R rear-facing space (opens in a new tab)
How is the Radian 3R different from the 3R SafePlus?
The 3R SafePlus follows the Radian SafePlus Series manual, which lists rear-facing from 4 to 50 lb, the forward-facing harness at 26.5 to 65 lb and booster mode at 40 to 120 lb. The 3R manual starts rear-facing at 5 lb and gives the same forward-facing and booster ranges.
How wide is the Radian 3R?
Diono lists it at 17 in wide, 16 in deep and 28.5 in tall, with a seat weight of 25.9 lb.
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
- Radian3R_Manual_NA_2026_V1_WEB.pdf
- diono.zendesk.com/hc/en-us/articles/18551446423315-Radian-3R-Manual
- Diono Radian 3R manual, 2026 (PDF)
- Diono Radian SafePlus Series manual (PDF)
- Diono support: Radian 3R SafePlus
- Diono support: Radian 3R dimensions
- Diono support: Radian 3R rear-facing space
- Diono support: Radian 3R 3-across
- NHTSA car seat guidance
Other Diono convertible car seats
| Model | Top child weight | Seat weight | Width | Usable life |
|---|---|---|---|---|
| Radian 3R All-in-One Convertible Car Seat (this seat) | 120 lb | — | — | 10 years |
| Radian 3QX SafePlus All-in-One Convertible Car 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 3RX All-in-One Convertible Car Seat | 120 lb | — | — | 10 years |
| Radian 3RXT All-in-One Convertible Car Seat | 120 lb | — | — | 10 years |