Review: Britax Römer BABY-SAFE i-SIZE Car Seat And BABY-SAFE i-SIZE FLEX BASE

Choosing car seats is always tricky. There’s so many on the market, all with different features and USP’s designed to give your child ‘the safest journey ever’. It can be confusing for experienced parents, let alone first-time parents delving into the world of baby products for the first time.

A car seat that particularly interested me when looking for one for ‘Beetle’ was the new BABY-SAFE i-SIZE car seat. As the name suggests, this is i-SIZE compliant and suitable for babies from newborn to around 15 months old (83cm). As huge fans of Britax Römer (we have the original DUALFIX and new DUALFIX i-SIZE), I was delighted when they agreed to send us one for review as part of their Britax Römer Ambassador Panel.

We’ve been using the car seat, along with the BABY-SAFE i-SIZE FLEX BASE, for the last four-ish months since ‘Beetle’ was born. These have been installed in both a Volkswagen Golf GTD and an Audi Q2. Below, you’ll find my review of the Britax Römer BABY-SAFE i-SIZE car seat with the BABY-SAFE i-SIZE FLEX BASE:

Review Britax Römer BABY-SAFE i-SIZE Car Seat And BABY-SAFE i-SIZE FLEX BASE ISOFIX newborn versus 4 month baby

Product Description

The product is described as:

Keep your little one safe on every journey with the Britax Römer BABY-SAFE i-SIZE car seat. It is designed to conform to the new car seat regulation ECE R129 (i-Size), the car seat is suitable from birth and allows your little one to travel rear-facing until they reach 83cm (approx. 15 month). It also features a patented recline mechanism which adjusts the seat, as you adjust the harness – for newborns, the seat is used in a lie-flat position to offer support to their underdeveloped muscles and keep them safe. For older babies the seat can be gradually moved in to a more upright position. The seat has also been designed with a superior side impact protection to keep your child safe in the event of a side on collision.

The Britax Römer BABY-SAFE i-SIZE car seat can be installed in your vehicle using the BABY-SAFE i-SIZE FLEX BASE for a firm and secure fit which also makes it easy to lift the seat in and out of the car at the beginning and end of your journey. With the Baby Safe i-Size Flex Base, you can adjust the base angle, providing an ergonomic, flatter position for your baby, keeping them comfortable and safe.

Product Experience

The BABY-SAFE i-SIZE Car Seat And BABY-SAFE i-SIZE FLEX BASE arrived together in the same box. On first examination, the base looked more compact and felt lighter than our previous ISOFIX base and the car seat looked very padded and comfortable. The car seat was Mineral Purple (seven other colours available too), which gave it a very striking appearance with the different shades of purple, touches of electric blue and black shell. Initial impressions were good.

Review Britax Römer BABY-SAFE i-SIZE Car Seat And BABY-SAFE i-SIZE FLEX BASE ISOFIX out of box

The first part to fit is the BABY-SAFE i-SIZE FLEX BASE which takes a few minutes. Basically, this connects to the ISFOFIX points in your car and remains in situ, allowing you to easily put in, and take out, the car seat. It comes with ISOFIX insertion aids to protect the car, however our cars have had these as standard so they weren’t required.

To install, you pull the grey lever at the front of the base which extends the ISOFIX locking arms. You then squeeze together the green safety button and red release button on both locking arms to open them up. The support leg then needs to be rotated from underneath the base until it is in a vertical position.

You then place the base on the seat of the car and position it so that the ISOFIX locking arms are in line with the ISOFIX fastening points on the car. You then push the base backwards so that the locking arms engage with the fastening points and the base touches the back seat – you’ll hear a click and see that the green safety buttons are visible to indicate that it is fitted correctly.

Review Britax Römer BABY-SAFE i-SIZE Car Seat And BABY-SAFE i-SIZE FLEX BASE ISOFIX green indicator light

You can now check that the support leg is fully rotated, that the red mark at the top of the support leg is no longer visible and that it is secured against the vehicle floor (using the grey adjustment buttons) – again, you should see a visible green mark to indicate it is fitted properly.

The final thing to do is adjust the inclination which is a very cool feature. The BABY-SAFE i-SIZE FLEX BASE takes into account your car’s seat inclination as these are all different – if your seats are quite inclined, you may find that your baby isn’t lying as flat as you’d like. To adjust, press the grey inclination adjustment button in the middle of the base, then lift up (or push down) the back of the base until the indicator on top goes from red to green.

Voila. It may sound like there’s a number of steps involved, but each one takes a few seconds meaning that the base can be installed in less than a minute. This is really handy if switching between cars.

Review Britax Römer BABY-SAFE i-SIZE Car Seat And BABY-SAFE i-SIZE FLEX BASE ISOFIX installed in car 1

Once you’re happy with the BABY-SAFE i-SIZE FLEX BASE, you can then install the BABY-SAFE i-SIZE car seat. This is achieved by simply popping the car seat onto the base (with the car seat facing backwards) until you hear a click as the fixation slots align with the fixation prongs. Again, you’ll see the indicators have turned green on both sides if it is fitted correctly.

Finally, make sure that the handle is in the upper position and unscrew the SICT (closest to the door, as there’s one on both sides) anti-clockwise so that it comes out. I’ve not seen one of these before, but it’s basically designed to provide additional protection in case of a side impact. Very clever – although it reminds me a bit of a door stop and is an additional thing you need to remember to do each and every time.

Review Britax Römer BABY-SAFE i-SIZE Car Seat And BABY-SAFE i-SIZE FLEX BASE ISOFIX SICT close up

To take the car seat off the base, you just need to screw back in the SICT, then pull and hold the grey release latch situated at the back of the car seat below the sunshade. This detaches the fixation prongs from the fixation slots to allow you to easily lift up the car seat from the base. You can, of course, install the car seat using the seat belt and marked blue sections on the car seat, but I much prefer using a base.

And that’s that. As the base remains in the car, you have the flexibility of easily putting the car seat into the car, and taking it out, in a matter of seconds. Yes, there’s an extra cost with buying the base, but I genuinely think it’s worth it as it’s quicker, easier, there’s no faffing with seat belts and you know it’s fitted correctly each and every time.

Personally, with a small baby, we’ve always liked having having a car seat which can be put into the car, then taken out of it, whilst the baby is inside. We’ll often put ‘Beetle’ into the car seat in the house, then stick the car seat into the car with him safely strapped in. It also helps if your baby falls asleep whilst driving as you can remove them from the car when you get to your destination and (hopefully!) keep them in the land of nod.

Review Britax Römer BABY-SAFE i-SIZE Car Seat And BABY-SAFE i-SIZE FLEX BASE ISOFIX in car with baby

Putting your baby into the car seat is pretty easy too. On first use – and as your kid grows – you need to make sure the height of the shoulder straps are correct. In the instruction compartment on the back of the car seat, you’re able to move the headrest and harness up or down by pressing the adjustment button. You know it’s correct as you’re basically looking for the headrest to be just above the shoulders.

But that’s not all. Adjusting the headrest height also changes the lying position of the car seat so that it’s best suited to your child. For a newborn, the low headrest height goes hand-in-hand with a flat lying position, which is the recommended position for a baby whose muscles are developing. As the child gets older, the headrest moves up, which in turn makes the lying position more upright to give the baby more space and increased safety. Very clever.

Review Britax Römer BABY-SAFE i-SIZE Car Seat And BABY-SAFE i-SIZE FLEX BASE ISOFIX kids in the back of the car

Once this is adjusted for your baby, you’re ready to put them into the car seat using the 5-point harness and comfortable shoulder straps. The straps can be loosened by using the adjustment button in between the baby’s legs, with either arm then put through the relevant gap of the shoulder and hip strap. The adjustment button is a little fiddly to find as you need to put your finger into a slot, but it ensures the baby can’t mess with it, and loosen the straps, when they’re older.

You then put the two buckle tongues on either shoulder strap together, click this into the harness buckle in between their legs, then pull on the dangling belt end which tightens the shoulder straps. To get them out, you press the red button on the harness buckle, then loosen the shoulder straps as mentioned above.

This entire process is simple and easy. Our little lad feels really secure and protected in the car seat, mainly thanks to the padding and 5-point harness. It’s a tiny bit more of a faff getting a baby’s arms into the 5-point harness when compared to a 3-point harness which just comes over the shoulders, but it definitely feels more secure. Having used 5-point harnesses on this and the DUALFIX, this is always my preference over a 3-point.

As we have a Britax Römer DUALFIX and DUALFIX i-SIZE, I do miss the car seat rotation that I’ve become accustomed to on those. Bascially, this allows you to swivel the car seat to face the door, which makes it easier to put your kid into the car seat as they’re facing you. I’d love for the BABY-SAFE i-SIZE Car Seat to rotate on the BABY-SAFE i-SIZE FLEX BASE, but that’s not possible at present.

Review Britax Römer BABY-SAFE i-SIZE Car Seat And BABY-SAFE i-SIZE FLEX BASE ISOFIX SICT baby in car close up

A few other things worth noting about the Britax Römer BABY-SAFE i-SIZE. The car seat comes with a removable newborn insert – this is designed to give extra support and comfort for young babies around the back, head and shoulders. We’re still using this at 4-months of age (around 15lb to 16lb), but Britax advise that it can be used up to around six months old, at which point it can be easily removed. I’d imagine we’d be removing it in the not too distant future though as our little lad isn’t so little now.

Secondly, the car seat handle can pivot (using buttons) and be set in three different positions – upright for carrying / transport in the car, tilted back to allow you to put the baby in the car seat, and all the way back so it’s touching the floor. The latter allows the car seat to be put onto the floor safely (with or without baby) and prevents it from tipping back – useful for when you’ve transported your baby somewhere in the car seat.

There’s also a sunshade, which offers protection for your child from the sun (UPF 50+) – this can be put up and held in place using hooks on the handle, folded back so it’s out of the way or removed completely. The car seat cover is machine washable and pretty easy to take off and put back on – considering how much babies and toddlers are sick and spill food / drink, it’s always an added bonus for this process to not be too complicated!

Finally, the car seat can also be attached to a pushchair with the relevant adaptors to turn it into a proper travel system. These need to be bought separately, however we’ve not bothered with this as we tend to use a baby carrier when we’re out for a long time, e.g. going into town, or just carry him in the car seat for short journeys, e.g. going from the car park to soft play.

Review Britax Römer BABY-SAFE i-SIZE Car Seat And BABY-SAFE i-SIZE FLEX BASE ISOFIX dad carrying car seat

And that’s pretty much it. If you’re looking for a Group 0+ / Phase 1 (birth to 15 months, 40 to 83cm) car seat, then you’re not going to be disappointed with the Britax Römer BABY-SAFE i-SIZE Car Seat. With the addition off the BABY-SAFE i-SIZE FLEX BASE, you have a great option for safe and comfortable travel with your little ones.


The Britax Römer BABY-SAFE i-SIZE car seat costs around £190 and the optional BABY-SAFE i-SIZE FLEX BASE would set you back another £150ish. If you shop around and bide your time, you’re likely to find a deal though, particularly if bought together – for instance, Mothercare were recently selling both for £270.


I’m a big fan of all things Britax Römer and the BABY-SAFE i-SIZE Car Seat with the BABY-SAFE i-SIZE FLEX BASE hasn’t let me down at all. Our son has been using it for the last four-ish months and will continue to do so until he’s grown out of it (or until L needs a new car seat, when we might switch him to her Britax Römer DUALFIX i-SIZE).

This does everything I’d expect from a car seat (and more!), including being i-SIZE compliant – something that all car seats will need to be in the future – which means it offers increased protection and safety for your little one. It’s also really simple to use and feels brilliantly made – I’ve had no issues whatsoever with putting ‘Beetle’ into the car seat or taking him out. Then there’s the cloever lie-flat technology and associated adjustable harness / shoulder straps which ensure your little one is in the best possible position.

With the BABY-SAFE i-SIZE FLEX BASE, you’re also able to put the car seat into the car, and take it out, in seconds. This is great for when you have a newborn as it makes life so much easier, for instance, putting the baby into the car seat and then into the car, or taking the car seat out when they’re still asleep. All of the red / green indicators, and the fact it uses ISOFIX, also ensures that it is fitted correctly each and every time.

In the interests of balance, I feel like I should come up with some negatives. Unfortunately, I have no major ones. My only little niggles are that the shoulder strap adjustment button is a little fiddly to get to as it’s sunken in the seat, and that the added padding and protection makes the car seat a little heavier. Other than that, I can’t fault it and would definitely recommend it to anyone looking for a newborn to 15 months old car seat – you’re not going to get much better than this!

The DADventurer Star Rating

5 out of 5 stars


Disclosure: The BABY-SAFE i-SIZE Car Seat And BABY-SAFE i-SIZE FLEX BASE were sent to me by Britax Römer with the purpose of writing an honest review in exchange for the product.