Review: Diono Radian 5 Extended Rear Facing Car Seat (Group 0, 0+, 1, 2)

When it comes to buying stuff for your baby, one of the most important purchases is the car seat. Not only is it a big lump of cash to pay out, but it’s the thing that protects your little one when driving. BUT, they can be confusing. As an expectant dad, I remember not knowing where to start. There seemed to be so many choices on the market, along with terms like ISOFIX, extended rear facing (ERF) and ‘groups’.

Having done our research, we decided to buy a Maxi-Cosi Pebble (Group 0+) with a 2WayFixBase before she was born. This was intended to last her for a year-ish until she grew out of it and we upgraded to the next Group. However, as Toddler L is a shrimp, it actually lasted a lot longer. Despite that, the day did eventually arrive when it was time to retire the car seat. This meant looking for a new one.

We didn’t have many requirements, but we did know that we wanted it to be an extended rear facing car seat. I’m not going to go into the stats, but plenty of studies show that it’s the safest way for your kid to travel. The UK’s i-Size regulation makes it mandatory for babies to stay rear facing until they are 15 months old, however many countries – particularly in Scandinavia – keep kids rear-facing until they are four years old. A such, we wanted the option of keeping her rear facing for as long as possible.

We tried the Joie i-Anchor, however we really didn’t get on with it. The straps felt really loose and Toddler L managed to get her arms out multiple times when we were driving. As a result, we weren’t happy using it and looked for another. I’d heard good things about the Diono Radian 5 and was lucky enough that they agreed to send us one to review.

Read on to find out what we thought about the Radian 5 – an extended rear-facing car seat which is suitable for your kid from birth to seven years old.

Product Description

The product is described as:

Radian 5 provides ultimate protection with extended rear-facing capacity and longer 5-point harness use when forward-facing. With a higher weight capacity, Radian 5 is the only seat which is suitable from birth, offers extended rear-facing and converts to a forward-facing car seat with a 5-point harness to 25kg.

The unique steel frame means although Radian 5 is a bit heavier, it is super strong to resist crash forces and offers the most amount of protection. Metal reinforcements and the best EPP foam combine to provide ultimate side impact protection, whilst the straight side walls ensure children stay contained in the seat during a crash. The narrow design takes up less space in the back because it’s not necessary to have thick plastic sidewalls.

With a rear-facing capacity up to 25kg, Radian 5 allows babies to travel in the safest position for as long as possible. Extended rear-facing can be up to 5 times safer as it protects and supports the neck in the event of a collision. A rear-facing car seat can also be more comfortable giving little ones somewhere to rest their legs.

When parents decide it is the right time to turn forward-facing, Radian 5 will keep little ones in a 5-point harness up to 25kg. Longer 5-point harness use prevents any seat belt escapes and misalignment when little ones are too young to understand the importance of the seat belt.

The convertible forward and rear-facing design of Radian 5 gives complete flexibility so the seat can be utilised in the best way that suits parents and their lifestyle. With, memory foam padding , longer seat base and a handy cup holder, Radian 5 ensures comfort on long trips as well as short journeys. Radian 5 also features removable washable covers and folds flat for convenience – another unique feature!


Product Experience

On opening the box, I was greeted with a number of different parts. This included the actual car seat, two sets of harness pads (infant and SuperGrip), crotch pad, safe stop attachment, tether strap and connector, rear facing base, cup holder, infant cocoon, rear facing bolster and the instruction manual. I also had an angle adjuster sent separately.

As the car seat spans birth to seven years old and is forward and rear facing, not everything was required at once – for instance, you only need a set of harness pads at any one time. It wasn’t quite the same as Ikea flat pack furniture, but assembly was required before use. You can’t just stick it in the car like I’ve been able to with other seats before.


Assembly wasn’t particularly difficult. Following the instructions in the booklet, I soon had the Diono Radian 5 ready for action. This included unfolding the base of the car seat, tucking the carry strap through a slot in the seat and fitting the detachable rear facing base. All of which were pretty self-explanatory – so much so, I even received help from the toddler…


Next, I needed to make sure that the shoulder straps and harness buckle were located in the right holes. After trying Toddler L in the seat, I decided that the harness buckle should be in Position 2 and the harness shoulder straps should be at the top of the three lower slots.

To make these adjustments to the shoulder straps, I undid the straps from the yoke at the back of the seat, threaded the straps through, re-slotted them through the chosen hole, then reconnected to the yoke. The harness buckle was similar – namely, pushing the strap through the hole and then pushing it back up through the different slot. The final stage was to adjust the side impact head support to the top position because the shoulder straps were in the lower position.

Now I could fit the Diono Radian 5 into our car. Having only ever fitted a car seat with ISOFIX, I found the process to be a little faffy and time consuming – but it was manageable. To do this, I put the seat into the car in the rear facing position and pushed the sticky out bits of the base into the gap of the car seat. I then took the seat belt and fed this through the tunnel – which runs in the middle of the car seat – and clicked it into the seat belt buckle.


Next, I pushed down on the seat, pulled the seat belt tight and fed any excess seat belt back into the bit where the seat belt comes out of (I’m sure it has a technical name). Now, I could secure the seat belt in place using the red lock-off clip which clipped around the seat belt.


The next bit was to secure the car seat using the tether strap and connector. I fed the tether connector under the runner on the front car seat and created a loop by feeding it through.


I could then attach the clip on the tether strap (located on the back of the car seat) to the metal loop on the front seat runner. I then pulled the tether tight until the indicator went from red to green to show it was securely in place.


The final part of installation was to push the front car seat backwards so that it could brace the back of the Diono Radian 5, then push the cup holder into place. As alluded to earlier, the installation was fine, but it was nowhere as simple as ISOFIX which literally clicks into place. I’m sure I’ll get better with practice, but the thought of taking out the car seat and fitting it into another car doesn’t really fill me with joy. I reckon it’ll be staying put for the foreseeable future.

Whereas I have no issue taking out an ISOFIX car seat and clicking it into another car within seconds, the installation process of a seat fitted with a seat belt feels more laborious. The reason though is down to weight – generally, ISOFIX is unable to hold as much weight as a car seat which uses a seat belt and tether. As such, the Diono Radian 5 will do your child up to 25kg – more than ISOFIX. So, really, you get to use the seat for longer, but have to deal with a bit more faff of installation.


A few other thoughts on installation. (1) My advice would be to read, read and read the instructions as they are a little confusing. The seat configures in numerous different ways, so not everything is relevant for you at that time. Similarly, you may have to do certain things based on your setup (e.g. I forgot to move up the headrest up based on having lower shoulder straps). (2) I found the installation videos on the Diono website to be really useful. (3) Don’t be worried if you have left over bits at the end. I was left with numerous components – the Safe Stop, the rearward facing bolster and infant cocoon – which I didn’t need at this point.

Putting your kid in and taking them out of the seat is straight forward and not dissimilar from other seats. It’s a five point harness, which means you feed an arm through each shoulder strap, connect the two buckle tongues together then push these into the buckle.


You then pull the strap at the bottom of the seat to tighten the harness around the shoulders and waist. The harness adjustment strap works on a ratchet system – meaning you pull it in short, sharp bursts – which is something I’ve not had on a car seat before. To undo, you lift a little trigger by the strap.


Now, I’ve had a few problems with the whole tightening of the car seat. For whatever reason, when Toddler L was in the car seat, the harness adjustment strap just didn’t want to tighten passed a certain point – a point which I felt wasn’t tight enough. Strangely though, when she wasn’t in the car seat, it would tighten all of the way. I’ve raised this with Diono, but at the time of writing, a reason hasn’t been found. I have however found a workaround – if I pull the straps at the back of the sat whilst pulling the harness adjustment strap, I can get the seat tight, safe and secure. Not ideal, but I’m OK with this.

A few other things to note about the Diono Radian 5 which I’ve been impressed with. (1) The cup holder – it’s hardly a technological revolution, but it works really well. In fact, you can have up to four holders attached to the seat to store things like drink, food and toys. This is really handy when distracting your kid on long journeys. (2) I’ve already mentioned about extended rear facing – something I’d not realised though is that this is ERF up to 25kg (6 or 7 years old). I’ve only seen ERF to about 4 years old with other seats, so I’m very impressed this does it for longer. (3) It’s very slim, which means you have extra space in the back of the car.


(4) The car seat has a full steel frame – at the time of writing, this is the only car seat with a complete steel frame to provide extra resistance if in a crash. Obviously I’ve not tested it in a crash situation, but I like the sound of steel protecting my kid. This does make it quite heavy though. (5) The Diono Radian 5 folds to make it easier to store or take with you. This is a pretty cool innovation, although as just mentioned, it’s not the lightest thing in the world. (6) It is suitable from birth to 25kg (6 or 7 years old). For me, this is a very appealing proposition as it would save having to buy additional car seats (apart from a Group 3).

We’ve been using the Diono Radian 5 car seat for three months now. Apart from the shoulder strap tightening issues at the start, I’ve not had any other problems. Obviously we’ve not used it as a forward facing seat yet, we didn’t use it when she was a baby and we’ve not washed fabrics (which are removable), so I’m unable to comment on those bits. But, based on the aspects we have used, I’m impressed.


The Diono Radian 5 car seat retails at £295, however at the time of writing, this had come down quite significantly to £225. With other extended rear facing car seats costing anywhere between £150 and £400, the Radian 5 is priced firmly in the middle.

I actually think this is a really good price – I’ve mentioned plenty of them above, but the thing that stands out is that it lasts from birth to 25kg. In theory, you only have to buy one car seat in the first seven years of your kid’s life. That seems really good value for money.



I really like the Diono Radian 5. I think it’s priced well, it’s sturdy, is designed to last and is extended rear facing (to 25kg!), which gets a big thumbs up from me. I also really like the fact it can replace the ‘normal’ way of buying car seats, i.e. needing to purchase multiple ones as your kid grows. As this is birth to 25kg, you’ve got around seven years of use. The does mean though that you can’t take the seat in and out of the car and attach to a pushchair, as we did when Toddler L was a baby.

I like that it has a five-point harness up to 25kg which is easy to clip together and that there’s plenty of room to get Toddler L in and out of the car. I have had a few issues with it not tightening around the shoulders, but as mentioned, my workaround is to pull the straps down on the back of the seat which helps tighten it. I also like the design, which makes it more slimline than other seats we’ve used.

I think the Diono Radian 5 is quite different to other car seats – different isn’t a bad thing at all though. The fact that it has a full steel frame, is foldable, uses memory foam and even has space for four cup holders, does make it a pretty unique product. Having said that, I think this means that the car seat isn’t for everyone. I think it really suits someone – like us – who wants the ability to choose how their kid sits in the car (i.e. extended rear facing). For others who aren’t as fussed about ERF, want ISOFIX or want ease of moving it, there’s probably better solutions.

All in all, I like the Diono Radian 5. It’s grown on me the more I’ve used it and I’ve really been able to see some of the benefits which make it unique.

The DADventurer Star Rating

4.5 out of 5 Stars


N.B. This review was written by me (Dave) and represents my honest opinion of the product. The Radian 5 car seat was sent to me by Diono with the purpose of writing an honest product review in exchange for the product.