Britax Römer Dualfix i-Size review

Our rating 
4.4 out of 5 star rating 4.4
User rating
£427.00 RRP

In a nutshell

A fantastic car seat that allows your little one to face towards the back for longer, but allows you to easily adjust and change their position. Probably too expensive for some, but fantastic safety credentials and comfort
Ease of installing
5.0 out of 5 rating 5.0
5.0 out of 5 rating 5.0
Safety features
5.0 out of 5 rating 5.0
4.0 out of 5 rating 4.0
4.0 out of 5 rating 4.0
Worth the money
3.5 out of 5 rating 3.5
Pros: 360-degree swivel base, rear and forward-facing, superior safety features, i-Size test, machine-washable cover, newborn insert included, comfortable and high-quality finish
Cons: Not easy to swap between, expensive
Skip to view product specifications

Key features of the Britax Römer Dualfix M i-Size

  • Age suitability: Birth to 105cm or 18kg (approx 4 years)
  • Rear-facing to: 4 years
  • Installation: Integrated Isofix base
  • Weight: 15kg
  • Dimensions: 48x74x44cm (h, l, w)
  • Features: 360 degree swivel seat, rear-facing up to 105cm
  • RRP: £430

Britax Römer is a German-based company with a combined German and British heritage. It developed its first children’s car seat in 1966 – and from then has made a name for itself in child safety, and manufacturing 90% of its seat in the UK or Germany.

Its new Dualfix M i-Size is an updated version of the Dualfix, now tested to the new i-Size regulations, and with a few new design features. It is a from-birth, extended rear-facing car seat with an integrated Isofix base and 360-degree swivel action.

I-Size child car seats – everything you need to know

It is certainly at the more expensive end of the scale of this type of car seat, with an RRP of £450. Cybex’s Sirona i-Size, for example, costs £300, while Nuna’s Rebl Plus i-Size Car Seat (£350). There are even cheaper alternatives, such as the Joie Spin 360 car seat which costs around £249, although a lot of these have not yet been tested to i-Size standards.

First impressions?

I immediately noticed the quality of the Dualfix M i-Size. We got the Blue Marble which is a stylish, understated colour, but you can also get some more exciting colours, such as Wine Rose or Fire Red. I was slightly surprised by the bulk of the product, but that’s mainly because I had never handled a seat in that Group with integrated Isofix base before.


Is the Britax Dualfix i-size suitable from birth?

Yes, the Britax Dualfix i-Size is designed to be used from birth and up to 105cm (or approximately 4 years). It certainly is suitable from birth, as it comes with a great newborn insert and is very plush, comfortable and supportive. It also has a very horizontal recline which is great for newborns.

The only downsize to using it from birth is that not travel system compatible, meaning it’s designed to stay put, so no carrying of newborn out in the car seat or fitting it on a buggy.

However, I know many who buy this type of carseat after the first 6 months, and still get good value use out of it.

How long do you think the Dualfix i-Size will last? 

It is always questionable whether the seat really will last the full 4 years especially rearward facing, but the Dualfix M i-Size still had plenty of growing room for my 2.5-year-old.

It has larger dimensions than some of its competitors such as the Cybex Sirona i-size. For example, it is 1cm wider, and 4cm longer, so will accommodate growing legs easier.

In addition, it is important to note, it is no problem if a child has to slightly cross their legs when facing the back.

How do you install a Britax Dualfix i-size car seat in the car?

Apart from the heaviness and bulk of the Dualfix, it is very easy to install. You install it with its integrated Isofix base, which is very easy to click into place.

  • You release the Isofix connectors by pulling a handle/strap in the base on the side where the connectors are.
  • This should extend the connector arms allowing you to click them into your Isofix anchor points – they show green when engaged correctly.
  • Then you push the seat back towards the car’s seat back as far as you can…
  • The support leg also extends easily and shows green when it’s secure.
  • The Dualfix also has an adjustable rebound bar, which allows you to fit it to your particular car seat more easily, as you can adjust the angle better.

Once all installed, it feels incredibly secure, giving you fantastic reassurance that it won’t budge. It’s also handy that the instructions are kept in a compartment in the seat – this means you always have them to hand.


Does it feel secure once in place?

Yes, I absolutely loved how secure the Dualfix M i-Size felt once installed. We also have the fantastic Joie Stages that is installed with the car’s seatbelt, which we still use when on holiday. But compared to a seatbelt installation, I must admit that the Dualfix Isofix base feels so much more secure. It just wasn’t going anywhere.

Does the Britax Dualfix i-Size have a swivel function?

Yes, the Britax Dualfix i-Size rotates, which is great for getting your baby in and out of the car,  Even my husband – who is usually left quite cold by baby product design features – thought it was revolutionary.

It’s so much easier to get our little one in and out of his seat. Especially as they grow into large toddlers, lifting them into a seatbelt-strapped car seat is a bit of a palaver (although definitely doable, we did it for quite a while). Our 2-year-old also liked the ease of it.


It’s also handy that you can so easily swap between rear- and forward-facing. If you have a really tall driver in our car, it’s great to have the option of a bit more space behind the driver’s seat – which forward-facing provides.

The best rotating car seats

What’s the harness like?

As with all of this carseat, the harness is great quality and easy to use, It has comfy padding and can be adjusted very easily so it snugly fits your little one, providing optimum safety.

Does it feel sturdy?

Yes, it feels incredibly sturdy, but also nicely finished, with clear guides and good quality materials.

What’s the headrest like?

The v-shaped headrest is designed to control the movement of your child’s head to ensure optimal protection in side collision, while also providing comfort. It’s also very easily adjusted in multiple positions. As you adjust the headrest, the straps automatically change fit as well, so it’s very easy to get the right level for your child.


Are there different seat positions? Does it recline?

There are lots of different seat positions including 12 recline positions in total across forward- and rear-facing.

How comfortable is it for your child – what did your children feedback?

My little one loved this car seat. He was very happy in it, didn’t get too hot and sweaty, and slept well in it.


Tell us about its safety features?

The Dualfix M i-Size has superior side impact protection, tested to the new i-Size regulations. It has integrated SICT protection that absorbs energy in the event of an impact. It also has Pivot Link Isofix system which directs the force of an impact, first downward into the vehicle seat and then forward more gently which reduces the risk of head and neck injury, especially when forward facing.

The fact that this seat is rear-facing for longer also greatly reduces the risk for your child.

What do you think of the size of the car seat? How easy is it to get in and out of the car and swap between cars?

This seat is not designed to be swapped between cars regularly. Even though it is incredibly easy to install, and adapt to different cars, it is 15kg and a bit cumbersome. So lugging it to the car is a bit of a faff – especially with the support leg always unfolding and getting in your way.

Will your children fit in it until they are 4 years old (up to 105 cm)? 

My older child had grown well beyond the 105cm by the time she was 4. However, if you’re child falls within the height parameters, I think the seat is generous enough to last. As mentioned before, it is a bit longer and winder than some of its competitors.


Is it easy to clean?

Oh yes. It features a machine washable cover that can be removed without un-installing the harness – hurray! If all seat covers were this easy to clean, our car seats would be much more pristine!

How heavy is it?

At 15kg (due to the heft of the Isofix base), this car seat is quite heavy and not designed to be swapped between cars regularly. We would also not take it on holiday by plane, as it’s a bit of a faff to carry about, the Isofix base’s leg making it very cumbersome.

What design feature do you like most in the car seat?

Is it value for money?

At £430, the Dualfix M i-Size is perhaps prohibitively expensive for many. We loved the seat, and it has made getting little one in and out super easy, has him happily snoozing. However, paying that much money? The brand makes a lot of how long it lasts you – as they point out “4 years, 200 weeks, 1500 days” it will see you through. However, it is so handy to have a Group 0 infant seat – which often allows you to use it with your pram and certainly lets you carry sleeping baby from car to house with no hassle. So realistically, you might be buying the Dualfix in addition to an infant carrier… at which point the value for money equation is getting trickier.

What’s in the box?

  • Carseat with integrated Isofix base
  • Infant insert

Are there any accessories needed or available?

  • Spare cover
  • Summer cover

Who is this car seat best for?

The Dualfix M i-Size is best for those who want an easy-to-use, superior quality and safety car seat, that will grow with your child. It’s not great for those who want a car that’s easily swapped between cars or those who travel a lot.

What do you wish you had known before you got it?

I wish I had known just how easy this kind of car seat makes getting older babies and toddlers into the seat. I had originally opted for a seatbelt-only car seat, but we now love using this one.

Would you recommend this car seat?

I would definitely recommend this car seat, if you have the budget. There are quite a few swivel seats out there now, but this one is such great quality – it has been a real pleasure and provides fantastic security and peace of mind.

MadeForMums verdict:

The Dualfix M i-Size delivers on safety and comfort, and will see you through until well into preschool age. It is very easy to use and gives you the feeling of ultimate safety. It seems a bit roomier than some others in the same group, and I will definitely be putting my little one in, rear-facing for as long as possible.

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Product Specifications


Brand Britax
Model Römer Dualfix i-Size
Price £427.00

Suitable for

Child age (approx) Birth to 4 years
Child Height Up to 105cm

Dimensions & Weight

Weight 15kg


Car seat installation Isofix base
Travel system compatible No
Positions of carry handle None
Removeable cover for washing Yes


Optional extras Summer cover,spare cover