Diono Radian 3R Review – Best Budget 3-in-1 Car Seat for 3-Across Fit

Diono Radian 3R 3-in-1 Car Seat

Diono Radian 3R

Overall Rating
Face Rear & Front

Looking for a great budget car seat but don’t want to miss out on premium features? Then the Diono Radian 3R could be precisely what you’re looking for. As a 3-in-1 convertible car seat, the Diono Radian 3R lasts long enough to ride a kid from birth to tween, going through three car seat stages rear-facing, forward-facing, and booster.

Featuring an ultra-slim design, the Radian 3R is friendly enough to fit 3 across in the back seat, making it one of the best options for big families with several children. Disappointingly, the 3R is the entry-level model of the Diono Radian 3-across car seats with less advanced features – But this does not mean it’s not safe.

Plus, it comes with a foldable body that gives great portability for air travel. This superior mobility combined with solid design, 10 years of lifespan, and multiple color options for both boys and girls means that the Radian 3R offers more than enough to justify its price tag.

*Price may change due to e-commerce platform and brand sales promotion.

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Diono Radian 3R Review - Best Budget 3-in-1 Car Seat for 3-Across

Pros & Cons

The good and the bad

What is it best for

Who we recommend it for

Value for Money

Is it worth the price tag?


Dimensions, weight, color, etc

Safety Rating

Crash tests, FMVSS213, SIP


Weight/height limits, airplane, etc


Install with LATCH or seat belt


Other car seats to consider

1. Pros and Cons



2. Who Is It Best For?

Will the Diono Radian 3R be a good option for your child and your family?

At first, it might seem difficult to pinpoint who the Diono Radian 3R is best suited to. It’s not as light as some lightweight convertible car seats for toddlers and it does not have head and body inserts, which are commonly included in most ultra-performance 3-in-1 car seats.

The answer lies in its slim design, foldable seat base, and long-lasting life. Despite my usual recommendation that all-in-one car seats should include inserts as cradles for small babies, the Diono Radian 3R is one of a few exceptions. It’s not as good as its premium models like the Diono Radian 3RXT, which is more suitable for newborns.

It has a 120-pound top weight limit and a 57-inch top height limit, making it good enough for your kids to travel until they can wear the vehicle’s seat belt for security. What’s better, it has the highest rea-facing weight limit50 pounds, making it one of the best car seats that rear face to 50 lbs.

Made of automotive-grade steel in the core frame, the Diono Radian 3R is sturdy enough to pair with its long 10-year lifespan.

Manufacturing with Diono patented technology that reduces force and absorbs energy, the Radian 3R performs well for protection. Worry about the Diono Radian 3R safety rating? Check what the manufacturer says and what we find beyond the crash tests.

Further Information

Best Car Seats for 3 across

3. Value for Money

Is the price tag worth it?

The Diono Radian 3R is significantly much cheaper than other Radian 3-across series models and most all-in-one car seats on the market.

At $199 or even cheaper (sometimes the price drops on Amazon for special sales), the Radian 3R is really low-priced, making it a great option for parents who are on a tight budget and looking to pick up their first car seat. Check out our post on cheap car seats.

Its performance is long-lasting and its lifespan saves a lot of budget on this gadget. A solid metal-framed body and side-impact protection ensure your child’s safety in the car seat. Memorial foam and breathable fabric seat cover provide comfort for the little passengers in the car seat.

The Radian 3R also comes with lots of extra details that add value: for example, the thin but sturdy body combines compatibility and protection into one.

Plus, the foldable design offers the greatest portability for air travel situations. Find more portable car seats if you want one for travel.

In this regard, it offers better performance than other car seats at a similar price.

Diono Radian 3R vs 3RXT and the Series

Car Seats Comparison Radian 3R Radian 3RX Raidan 3RXT Raidan 3RXT Safe+
Price $199.99 $299.99 $349.99 $349.99
Weight limits (lb) RF:5-50 / FF: 22-65 / Booster: 40-120 RF:5-50 / FF: 22-65 / Booster: 40-120 RF:5-50 / FF: 22-65 / Booster: 40-120 RF:5-50 / FF: 22-65 / Booster: 40-120
Height limits (in) RF:44" / FF: 49" / Booster: 57.1" RF:44" / FF: 49" / Booster: 57.1" RF:44" / FF: 49" / Booster: 57.1" RF:44" / FF: 49" / Booster: 57.1"
Rear Facing Weights Up to 50lb Up to 50lb Up to 50lb Up to 50lb
Newborn travel high wedge - -
2-in-1 Infant positioning liner - -
Infant head support liner - - -
Newborn Protection Insert & Harness Pads - - - 3-Stage
Memory Foam Comfort+ Cushion
Safe+ Anti-rebound bar - - -
Extended Sidewalls for enhanced SIP - - -
Side Impact Protection - - - 6 layers
Storage Compartment for latch & rear-facing tether - - -
Headrest - Safe+ 12 position 12 Positions Safe+ 12 Positions
Cup Holder - Two Two Two XL
Fit 3-across
Width (in.) 17 17 17 17

4. Design

Dimension and Width

It’s a slim car seat – that should be the first impression you get when you look at the Diono Radian 3R. 

Yes, this car seat comes with a very thin body compared to other bulky ultra-performance all-in-one models like the Graco 4Ever DLX.

The width is as narrow as 17 inches. That’s why it is a great option among the 3 across car seats. 

3-across should be the most famous feature of the Radian 3-series from Diono, who might be the first company to explore and launch this type of car seat to satisfy the needs.

Graco also released another car seat – SlimFit3 LX, which aims to achieve 3-across. It’s even a bit narrower than Radian 3R with a 16.7-inch width. If you want to find which is better, check our post on Graco SlimFit3 LX vs Diono Radian 3R.

The depth of this car seat is very low as well, only 16 inches, and can be installed on most vehicles’ back seats. 

Most complaints about the size of Diono Radian 3R fall on the height of the car seat. It’s up to 28.5 inches, good for working with long-lasting performance till your child’s tween.

But it takes up more space from the driver or front passenger in the front seat, especially when it’s installed rear-facing for small babies and infants with the reclines needed.


Diono Radian 3R gets a high score on portability, with a rating of 8.

It’s the best among boosters, convertibles, and all-in-one car seats. Just not as well as an infant car seat.

It beats other models not just for its slim body, but also for its foldable design. The seat base can be folded and attached to the high back, making it portable and easy to carry wherever you go. 

However, it’s a bit heavy compared to most models from other car seat brands – up to 25.9 pounds. This might be caused by its longer highback. 

The installation is said to be a bit difficult, even with the LATCH. Supposedly, the lack of reclines and highback results in this. 

That’s why we don’t recommend you to switch it from vehicle to vehicle. Hard installation and a heavy body are a big problem for most moms.

But its folding design compensates for this. After all, it’s more convenient to carry it from home to the airport than other ultra-performance all-in-one car seats if you’re planning to take your baby for air travel.

Foldable Base for Best Portability

How to unfold and fold Diono Radian 3R?

1. Place the car seat on its back on a flat surface and unfasten the red carry strap from the bottom. Be sure the harness adjuster moves freely and is not locked within the bottom of the seat. 

2. Rotate the bottom until you hear it “click”, this confirms the car seat is locked for use. 

3. Check proper operation — Pull harness adjusting strap until harness begins to tighten. If it does not tighten freely, check the belt path on the back of the seat bottom is clear from obstruction. To fold the seat, release the levers as shown and repeat the above steps in reverse. 

4. Tuck the red strap through the harness slot and store it behind the cover. 

5. To fold, push the lever shown and secure with red strap.

Further Information

Best Foldable Car Seats

No Cup Holder

The Diono Radian 3R does not have a cup holder. None on either side.

That should be a major negative point for its overall performance. It’s common for kids and parents to have a drink or enjoy snacks in the car. But there is no place to hold the drinks or snacks and you need to find other alternatives or accessories.

Its advanced editions – 3RX, 3RXT 3QX, and 3QXT will have one or two cup holders. They are more expensive. 

It seems the cup holders are a factor for the Diono company to set a price for their car seats.

The Radian 3R is cheap at $199.99, with no cup holders. The other variants are priced higher, with cup holders. 

However, if you have solutions for carrying your child’s drinks or snacks, never mind about this.

Headrest and Harness

Designed to grow with your child, the Diono Radian 3R features a 10-position headrest, which is used to hold and protect the kid’s head. 

It’s commonly made of breathable fabrics to keep your child comfortable in the car seat. The padding inside offers two layers of side impact protection that helps avoid sudden shocks for any crashes.


Made of baby-safe textiles and washable fabrics in the seat pad and outer, the Diono Radian 3R is budget but looks great.

The inner foam and thick padding around the body and head ensure both safety and comfort. The steel-reinforced frame is strong for durability and safety in case of any crashes. 

Five different available colors for toddler girls and boys, but a few parents do not like its unisex design.

5. Diono Radian 3R Safety Rating and Crash Tests

As an entry-level all-in-one car seat, the safety rating for Diono Radian 3R is not as high as other models from its own 3-series or other brands.

But this does not mean the Radian 3R is not safe to ride your child. 

Actually, all the car seats sold on the US market are required to pass the most rigorous crash tests and standards from the US and Europe before going to market for sale. So does Diono Radian 3R. 

It meets or exceeds the child restraint criteria for a frontal crash test under the US FMVSS 213. It also features a 5-point harness for protection. 

The manufacturer boasts of its reinforced steel core that is mechanically engineered and made from automotive-grade high-density plastic and steel, creating the ultimate protection for the little passengers.

Along with its SafeStop patented technology that will reduce forces and absorb energy on forward-facing harness mode from 22 to 40 lb, the Radian 3R earns a high score on protection performance.

Plus, the aluminum reinforced sides and thick energy absorbing foam work together to distribute crash forces for full shielding upon side impact. 

However, it lacks an extra headrest that is used to add protection to your child when there are any crashes from the side. 

It does not have a head or support insert either, which is good for fitting small babies for optimal protection. That’s why the car seat is used for newborns at least 5 pounds or heavier.

6. Performance

3-Across Fitting

Diono is a creative manufacturer to develops a lot of models that fit three across, including the Radian 3R.

Its slim body earns a great deal of praise among big families who have two or three kids to ride in the car seat.

However, you should never place the car seat overlap with other car seats, avoiding any loose and incorrect installation.

Luckily, no cup holders on both sides help avoid this case.

Diono Radian 3R Fit 3 Across

Weight and Height Limits

The manufacturer boasts that Radian 3R is designed to ride a newborn as small as 5 pounds.

The 5-pound minimum weight requirement is not as good as other convertible or all-in-one car seats with a lower 4-pound, but still good for babies from their birth.

It’s a pity that there is no body insert for small babies. 

It seems the Diono Radian 3R is good for big infants and toddlers. The top rear-facing weight limit is as high as 50 pounds. It’s the cheapest rear facing car seat up to 50 lbs.

That would be great if you’re living in the states that require children to face the rear until 2 years old, as this 50-pound weight limit can allow most toddlers to stay rear-facing as long as possible.

Its highback comes in handy for this case now. 

The rear-facing height limit is not specified in the product description, but we find that the manufacturer mentions a top rear-facing height limit of 44-inch in the user manual. It’s not the 57-inch as we thought as the booster mode, nor the 49-inch as the forward-facing mode.

But that’s good enough for most infants and toddlers to stay rear-facing as long as possible until they are two or three, even four years old.

The weight and height limits for forward-facing and booster are very common as most child restraints: 65-pound and 48-inch for the 5-point harness; 120-pound and 57-inches for the booster mode. 

These are the average performance for most child restraints for the forward-facing stage and booster stage.

There are a few models that will increase the top weight limit to 120 pounds and the top height limit to 63-inch. They are designed for big kids who grow faster than their peers.

To use Diono Radian 3R in booster mode, your kids should be 4 years or older. That’s the minimum age requirement for all the boosters sold on the US market because the 4-year-old is the basic condition that the child car seat regulations ask.

Age Range/Longevity

As a 3-in-1 car seat throughout three car seat stages, the Diono Radian 3R is intended to serve your kids for a long time, up to tween. 

This is as common as other all-in-one car seats, which are considered to be a money saver, thanks to their long usage and lifespan.

The Radian 3R has a 10-year lifespan that starts from the date of manufacture, not the date when you purchase it. But that’s long enough for your child to grow from newborn till the day when your kid stop using a car seat. 

For example, you purchase the Radian 3R on the second year of manufacture date. But there are still 8 years left before it’s expired.

That means, your kid will stay in this child’s car seat from birth to his/her 8th birthday, which is the legal age for a kid to get out of child restraint.

If you use a Diono Radian 3R 3-in-1 convertible car seat until the last day when it gets expired, check this post on what to do with expired car seats.


The Diono Radian 3R is designed to grow with a kid from newborns to preteenagers.

With no doubt, this child car seat is suitable for all the first three car seat stages (based on the definition of NHTSA) – rear-facing, forward-facing, and booster. 

It combines three car seat types into one – infant, convertible, and booster, starting from a child’s birth and ending at a child’s tween.


Is a Diono Radian 3R 3-in-1 car seat allowed on planes?

Yes. In the user manual, you’ll find the statement that Diono Radian 3R is certified for use in aircraft in harness mode.

Booster mode is NOT allowed for air travel. 

That’s the same rule for all boosters or booster mode in a multi-stage child car seat. Because boosters need a shoulder belt, which is not included in the seat belt system on the plane, for secure installation.

It’s STRONGLY recommended to call the airline to make sure this car seat can be installed on their planes before onboarding.


How long is Diono Radian 3R 3-in-1 car seat good for

Up to 10 years of time from its manufacturer date. 

The Diono Radian 3R has a lifespan of 10 years of usage. That’s the longest of the car seats. Most all-in-one or convertible car seats are manufactured to last so long to grow with your kid. 

But that’s not the case in real use. The 10 years of lifespan starts from the date it was manufactured, not the day you purchase the car seat. You can find the sticker on the back of the car seat.

If your child grows slower than their peers, a cheaper backless car seat is also a good option if the car seat is expired.

Further Information

When do Diono Car Seats Expire


The warranty for Diono Radian 3R absolutely adds a lot of points to its overall score. More than the 12-month standard warranty starting from the date of original purchase, the Diono offers an extra 24-month warranty for this child restraint system. 

That means, you’ll get a total of 36-month warranty. The only condition is that you need to register with your order information. But that’s a quite simple step for most parents. 

It’s commonly the first step if you’re planning to use the car seat for a long time, without a return.

7. Diono Radian 3R Installation

Which Installation Method Should I Use?

This car seat can be installed in your vehicle using either the vehicle seat belt or the LATCH system.

Both ways are equally safe to ride your child as long as you install it properly following the Diono Radian 3R user manual. It’s NOT allowed to use both methods at the same time.

Rear-facing Installation for Diono Radian 3R

Rear-facing Installations Tips for 5–50 lb (2.3–22.7 kg) 

  • Choose LATCH, lap belt, or lap-shoulder belt to install the Diono Radian 3R.
  • LATCH can be used for installation for infants between 5–35 lb (2.3–15.8 kg), DO NOT install by this method for a child weighing more than 35 lb (15.8 kg).
  • You should reinstall with a vehicle belt for weights between 35–50 lb (15.8–22.7 kg). 
  • Infants who weigh less than 22 lb (10 kg) and are under 1 year old, MUST use this car seat rear-facing. 
  • Place the car seat rear-facing in the vehicle back seat. 
  • Make sure the LATCH strap or vehicle seat belt is routed through the rear-facing belt path marked with the blue text and rear-facing illustrations. 
  • Install this car seat tightly in your vehicle. The car seat should not move at the rear-facing belt path location by more than 1 in. (2.5 cm) from side-to side, front-to-back. 
  • If using a lap belt only, refer to your vehicle’s owners manual for installation advice. 
  • Harness straps MUST be at or just below the top of your child’s shoulders. 
  • Place the chest clip at armpit level. 
  • Never place a rear-facing car seat in the front with an airbag on.

Forward-facing installation

  • You can choose to install Diono Radian 3R with LATCH, lap belt, or lap-shoulder belt.
  • NOTE: If the child is UNDER 40 LB (18 KG), install the Diono SafeStop by following the instructions on LATCH before proceeding. IMPORTANT: The SafeStop will need to be removed once the child reaches 40 lb (18 kg).
  • NOTE: If the child is OVER 40 LB (18 KG), go to step 1 of Installation using a Lap/Shoulder With 5-Point Harness. IMPORTANT: If the child is OVER 25 LB (11.3 KG), lower the adjustable bottom by following the instructions in the car seat manual. 
  • NOTE: For forward-facing installations using a LAP BELT ONLY with NO top tether anchor point available, you MUST install the Diono Lap Belt Cushion by following the instructions in the car seat manual before proceeding; otherwise proceed to the next page.
  • Lift the bottom bar up and over the inside channel toward the seat bottom to release. Confirm locked.
  • Make sure the LATCH strap or vehicle seat belt is routed through the forward-facing belt path marked with the red text and forward-facing illustrations. Install this car seat tightly in your vehicle.
  • The car seat should not move at the forward-facing belt path location by more than 1 in. (2.5 cm) from side–to– side, front–to–back. If using a lap belt only, refer to your vehicles owners manual for installation advice.
  • Harness straps MUST be above the top of your child’s shoulders. Place chest clip at armpit level.
  • The American Academy of Pediatrics (AAP) and NHTSA recommend that children be rear-facing until they reach the maximum rear-facing height and weight. This car seat can remain rear-facing up to 50 lb (22.7 kg).

Booster Installation for Diono Radian 3R

  • For 40–120 lb (18–54 kg) 
  • Use ONLY the vehicle lap/shoulder belt system when restraining the child in this booster seat. DO NOT USE A LAP BELT ONLY!
  • Make sure the vehicle seat belt can properly retract before each use.
  • If a 5-Point harness is installed, please review the harness removal section. The 5-Point harness MUST be removed to use this seat in booster mode. 

1. Place the child in a seat with their back flat against the back of the booster seat. 

2. Slide vehicle’s lap/shoulder belt through booster belt guide over seat . 

3. Buckle the vehicle lap/shoulder belt. Be sure the lap/shoulder belt lies across your child’s shoulders, between the neck and edge of the shoulder. Be sure the lap portion of the vehicle seat belt goes under the side nubs and 3 the belt lies low across your child’s hips.

Diono Radian 3R Car Seat Manual

The user manual is the most important thing you need to make sure it’s included in the package. You should always read the user manual before starting to install and use it for riding your child. 

The user manual of Diono Radian 3R is stored in a small storage bag on the back, but you can always find the online user manual on its official website, or download the PDF here.

8. Specifications







Suitable for

Newborns, toddlers, and big kids


Rear-facing and forward-facing



Portability (1-10)

8. Slim but a bit heavy duty

Weight (lb.)


Weight limits (lb.)

5-50 for rear-facing, 22-65 for 5-point harness, 40-120 for highback booster

Height limit (inch)

44” for rear-facing, 57” for forward-facing and booster


17 x 16 x 28.5″ WDH

Cup holder




Age Range

0-10 years old


1st, 2nd, 3rd


0-10 years old


LATCH and seat belt

Headrest Positions


Recline Positions





10 Years

Extra Features

Fit 3 across, folding design for portability

Diono Radian 3R vs 3RX vs 3RXT vs 3QX vs 3QXT

Car Seats Comparison Radian 3R Radian 3RX Raidan 3RXT Raidan 3QX Radian 3QXT
Price $199 $269 $329 $369 $399
Weight limits (lb) RF:5-50 / FF: 22-120 RF: 5-50 FF: 22-120 RF: 5-50 FF: 22-120 RF: 4-50 FF: 22-120 RF: 4-50 FF: 22-120
Rear Facing Weights Up to 50lb Up to 50lb Up to 50lb Up to 50lb Up to 50lb
Newborn Protection - - 2-in-1 Advanced 3-in-1 Advanced 4-in-1
Safe+ Engineering - - -
Head Support - 12 Positions 12 Positions Safe+ 12 Positions Safe+ 12 Positions
Cup Holder -
Fit 3-across
Width (in.) 17 17 17 17 17

9. Alternatives

What other 3-in-1 car seats should you consider?

Graco SlimFit LX 3-in-1 Car Seat

Graco SlimFit3 LX

Why is it better than the Diono Radian 3R?
Why its worse than the Diono Radian 3R?
Graco 4Ever DLX 4-in-1 Car Seat

Graco 4Ever DLX

Why is it better than the Diono Radian 3R?
Why its worse than the Diono Radian 3R?