Diono Radian 5 Car Seat review

Our rating 
4.0 out of 5 star rating 4.0
£295.00 RRP

In a nutshell

A multi-stage, rear facing for longer seat that has a harness up until 25kg, but not great for infants as recline features are poor
Ease of installing
3.0 out of 5 rating 3.0
5.0 out of 5 rating 5.0
Safety features
5.0 out of 5 rating 5.0
3.5 out of 5 rating 3.5
4.5 out of 5 rating 4.5
Worth the money
3.0 out of 5 rating 3.0
Pros: 5-point harness, birth to six years, fully steel frame, narrow design could fit three seats in some cars
Cons: Heavy, complicated to install, not ISOFIX compatible, makes driving difficult when rear-facing
Skip to view product specifications

The Diono Radian 5 Group 0+/1/2 car seat launched in February 2016 costing £295 and has the benefit of allowing children to sit rear-facing up to 25kg, or around age six, as well as the option of forward facing.


The Radian 5 is the latest in a series of car seats from the company Diono, which has a 15-year pedigree in the UK, having first set up in 2001 under a different name.

The Radian 5 prides itself on its fully steel frame, which means less padding at the sides and a slightly narrower design than similar seats and also has a unique folding mechanism – so it can be stored easily and even carried in a travel bag.

With its feature of being rear-facing for longer, the Radian 5 is comparable to other multi-stage seats like the Cybex Sirona (£375) and Recaro Zero.1 Elite (£435), but the main difference is that both of these seats are fitted using ISOFIX, whereas the Radian fits with a seat belt.

The price is closer to seats like the Joie Every Stage (£200) and Graco MilestoneBe Safe iZi Plus (£179), but both these do last an extra six years – up to age 12, or 36kg.

We tested the Diono Radian 5 with my almost five-year-old son, and 21-month daughter, in both forward and rear-facing positions, for journeys in our VW Golf ranging from a few minutes up to three hours.

The Diono Radian 5 is rear-facing to 25kg (around 6 years) what do you think of that?


I’m a bit of a stickler for car seat safety (aren’t we all!) so I was very excited to hear that Diono had come up with a product that could be used rear-facing up to the age of six.

Tests have shown that rear-facing is up to five times safer in a collision, so this is a big plus point for me on this seat.

My son is coming up to 5 and when I looked at the seat in its rear-facing position, I was a little dubious about the lack of room as his legs were bent up.

He’s 110cm tall, and the Radian 5 can apparently accommodate a child up to 122cm rear facing (and 144cm forward facing) with the 5-point harness.

But despite my misgivings, he told me that he actually preferred sitting rear-facing. We even tried the seat rear-facing for a longish journey of two hours, and he was quite happy in it.

My daughter is approaching two and already sits rear-facing in her Cybex Sirona car seat, so there were no issues there.

Is it easy to install the Radian 5 in the car?

No.  It took about 45 minutes to install in the car, as it was quite tricky to get the tether strap fastened onto the hook in the boot when forward facing, and it took a long time to figure out how and where to attach the tether strap when rear facing.

Personally, I found the 24 pages of the instruction book like attempting to decipher a guide to the Large Hadron Collider, but thankfully there are also instruction videos online.

Be warned that the helpline is only manned 9am-5pm Monday to Friday if you have any questions about the seat at weekends or evenings!

How do you install the Radian 5 in the car?

In the forward-facing position, the Radian 5 sits directly on your car seat and is secured with your car’s three-point seatbelt through a slot in the base.

A tether strap on the back of the seat threads down into the boot of your car a bit like a guy rope on a tent, where it fastens on to a catch in the boot.

In the rear-facing position, it’s a bit more tricky, as a separate base has to be clipped onto the Radian 5, which gives it the correct angle.

It then fastens in using the seatbelt and the tether strap. As we had no clip for it to attach to in the front of our car, we had to use the included tether connector as well. This knotted onto the front seat frame, and could then attach to the tether strap.

To be perfectly honest, I thought that having all the separate connector straps was slightly worrying as there is a lot of margin for error in connecting them.  And it’s certainly worth bearing in mind that this seat needs to be installed using tether straps as well as the seat belt, as the extra connection did prove a bit of a faff and not all car seats have top tether capacity, so check before you buy. 

Saying that, the seat certainly feels very secure once it’s all installed properly, but I didn’t feel that happy knowing that I might not have connected everything correctly.

How is strapping the kids in?

One of my favourite features of the Diono Radian 5 is the fact it has a five-point harness whether used rear or forward-facing.

The straps are easy to adjust once your child is in the seat by pressing on a catch that’s hidden away at the front of the seat and pulling on the straps to extend them. Once you’ve got the harness buckled up, you pull on a strap between their legs to tighten the shoulder straps. 

The shoulder straps can be adjusted to three different heights when the seat is forward-facing, and five different heights when rear facing, while the harness buckle strap between your child’s legs can be used in two positions.

What’s the headrest like?

The extendable headrest can be adjusted up or down depending on the height of your child, and has winged sides to cushion your little one’s head.

I personally found the adjust quite basic as it just involves pulling up or pushing down the headrest but the multiple positions – I managed to count 10 – mean you’ll find a height to suit your child.

How many recline positions does the Diono Radian 5 have?


I wasn’t very impressed with the recline on the seat as there are only two positions, and it can’t be adjusted while your child is in the seat.

The recline can also only be used when the seat is forward-facing, and has to be done before you get the seat in the car, so it’s not exactly user-friendly.

It’s easy enough to adjust the recline – it’s a very basic locking bar that has to be pulled manually to move the base into a different position – but as it has to be done before you attach the seat in the car, it means going through the rigmarole of removing the seat each time.

Do you worry that the recline position is too upright, particularly for a sleeping baby?

Yes, there wasn’t much of a recline at all, and no recline when rear-facing, so smaller babies and infants have to sit upright. 

While my two-year-old daughter will happily drop off in most positions, I would prefer there to be more recline to the seat.

It is a Group 0+/1/2 seat, is there much difference between the stages?

Essentially, the seat remains the same throughout the stages.  

But items such as the moveable headrest, different positions for the shoulder straps and harness buckle, and the infant cocoon with extra support around the head, body and legs for young babies, means the seat changes according to the age of the child using it.

Does it feel sturdy?

The Diono Radian 5 definitely feels sturdy once it is fully strapped in the car.

It is rather heavy, weighing around 11kg, but this is probably down to the fact its frame is fully made of steel, a fact Diono is especially proud of.

Diono also offers a lifetime warranty for the seat (around 10 years) so I’d be confident it would go the distance.


How comfortable is the Diono Radian 5 seat?

With features like memory foam and expandable seat sides, the Diono Radian 5 does make for a comfy ride, and my son seemed to really like travelling in the seat.

Is the Diono Radian 5 i-size?

No, it’s not i-Size (the new European standard for child car seats – which was introduced in 2013 and requires the seat to be fitted using ISOFIX) it conforms to the older, but still safe, R44/04 standard.

Saying that, it does meet and exceeds the newest laws that require little ones to sit rear-facing for longer.

Want to know more about car seat laws?  Then check these out:

Is it both a good rear and forward-facing seat?

Yes it is. We tried it in both positions, and it felt safe, secure and comfortable, once we had it properly installed.

The main downside when rear-facing is that it’s a big seat that takes up a lot space behind the driver’s seat.  So my 6ft 3 inch husband was not able to drive the car when we had it positioned there.

Even my short legs (I’m 5ft 3ins) felt a bit cramped up and I don’t think that our VW Golf is a particularly small car. 



Is it high enough for little ones to see out of the window when rear-facing?

Both of my little ones could see out of the window when rear-facing, despite the Radian 5 having a low profile to the back seat, but a younger baby might struggle.

What do you think of the size of the car seat?

One of the advantages of this seat is that it is relatively narrow at 45cm in width compared to the Joie Stages at 55cm and Graco Milestone at 50cm, so some larger cars would be able to fit three across the back seat.

We would struggle to fit more than two in our VW Golf, but there would certainly be a little more wriggle room for any adult who has to squeeze in the middle of the back seat.

Is it easy to clean?

The fabric cover is made of 100 per cent polyester and is machine-washable, which is great to know.

I also found it easy to wipe clean, and the three colours – black, plum and lagoon – are unlikely to show up stains.

Is there anything unique about the seat?

One unique feature about the seat is that it can be folded flat, which is really useful if you need to store it away.  It definitely means it’s easier to store than most similar car seats.

You can also buy a Diono Radian travel bag (£50), which the Radian 5 can be stowed in and carried as a backpack or shoulder bag, which could be handy if you want to take the seat on holiday with you rather than hiring one at your destination.

Is the Diono Radian 5 value for money?

At £295 it’s definitely not cheap but, if you take into consideration that you could use it from birth up to age six, you are saving on buying separate car seats.

The main downside is that it couldn’t be used as part of a travel system, or to transport a small baby easily by hand, so you might still need a Group 0+ seat anyway.

But the great thing about the Radian 5 is that you get a lot of bang for your buck as the package includes everything you need to get going with the seat – as well as a few extras, like the cup holder and super grip harness pads.

The infant cocoon is also included, which is a benefit as some manufacturers sell them separately.

Overall, £295 is good value as you are essentially getting three car seats in one – but the fact the Radian 5 is not travel system compatible is a slight negative.

What’s in the box?

  • Diono Radian 5 seat
  • Set of from birth harness pads
  • Set of super grip harness pads
  • Infant cocoon
  • Safe stop
  • Tether strap and connector
  • Rear facing base and back pad
  • Cup holder

Any additional extras?

  • Diono Radian travel bag  – £50
  • GripIt (A full seat surface protector mat) – £24.99
  • My Stuff (Storage pocket for your child) – £5.99
  • Stuff’n Scuff (Vehicle back seat protector) -£13.50
  • Travel Bag (Waterproof backpack or in-hand bag for transporting the carseat) – £17.20

MadeForMums verdict:

The Diono Radian 5 multi-stage car seat is a sturdy and comfortable seat with some well thought out safety features but lacking some of the panache of its pricier rivals. 

Safety has been placed at the top of the priority list with this seat, with its steel frame, reinforced sides and super grip harness pads to reduce the impact of crash forces, while the lifetime warranty offers peace of mind.

It’s not for those who want an i-Size seat as it’s not ISOFIX compatible, but for seatbelt installation car seat safety from newborn to age six, this seat could be the answer.


Want more multi-stage car seats, then check these out…

Product Specifications


Brand Diono
Model Radian 5 Car Seat
Price GBP £295.00

Suitable for

Child age (approx) Birth to 5 years
Child weight Up to 25kg

Dimensions & Weight

Weight 11kg


Car seat installation Non-isofix base
Travel system compatible No
Positions of carry handle None
Removeable cover for washing Yes
  • Suitable from birth with extended rear facing capacity to 25kg forward-facing 5-point harness capacity from 9kg up to 25kg full steel alloy frame creates the strongest car seat available v3 energy reduction system provides ultimate protection in all collision situations – forward
  • Rear
  • Side impact or overturning supergrip energy absorbing harness pads significantly reduce the impact of crash forces to the child deep and straight side walls ensure maximum containment and comfort and provide complete head to hip protection aluminum reinforced side-walls and headrest resist crash forces all round energy absorbing epp foam engineered plastic shell for strength and durability unique safe stop attachment to absorb more crash forces expandable sides and extendable headrest to grow with the child as they reach each milestone
  • The first convertible car seat with a fold flat mechanism for easy storage and transport super soft fabrics with a cosy infant support cushion and headrest longer seat bottom for leg support a


Optional extras Diono Radian travel bag - £50,GripIt (A full seat surface protector mat) - £24.99, My Stuff (Storage pocket for your child) - £5.99,Stuff’n Scuff (Vehicle back seat protector) - £13.50,travel bag (Waterproof backpack or in-hand bag for transporting the carseat) - £17.20