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Isofix baby car seats

The best and worst Isofix baby car seats for 2020

Article 2 of 3

Which? crash tests every Isofix child car seat reviewed. Here are the best and worst we've tested of Isofix models on sale

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Isofix is a type of child car-seat fitting system that should make it easier for you to fit your baby or child car seat. We examine and assess the most popular Isofix and other car seats, putting them through our tough crash tests. 

The best Isofix child car seats

Below, we've picked out the best and the worst from our most recent tests, or high scorers from previous tests if they're still available, so you can instantly choose which to add to your shopping list of Isofix child car seats. 

Our table below shows the top five Isofix child car seats from our stringent tests. But do also take a look further down the page at the worst Isofix child car seats we've tested. These are the ones with the lowest scores, so you can compare and make sure to avoid. 

Only logged-in Which? members can view our recommendations in the table below. If you’re not yet a member, you can get instant access by joining Which?.

Top scoring Isofix child car seats


This Best Buy car seat enables your baby to lie flat, which is the safest position and best position for them to travel in. Its i-Size approved and installed using the Isofix base, which can be used with the next seat up, once your baby outgrows this seat. It gets an excellent five stars for safety in our crash tests.


This i-Size car seat gets a good four stars for overall safety. It has a 360-degree rotating base so it can be used rear or forward-facing, and the swivel feature also makes it easier to put your child in and remove them from the seat. The side-impact panels automatically pop up when the harness is tightened so you never drive off without them activated.


As with its predecessor, this i-Size car seat is a Best Buy. It’s extended rear-facing and gets five stars for overall safety, indicating a very low injury risk in a front or side collision. The seat is spacious and well-padded, and the adjustable Isofix connectors give your child more legroom and they enable the seat to have a secure and stable fit in the car.


This i-Size car seat is approved for use in aeroplanes and it’s compatible with a number of Best Buy pushchairs as part of a travel system. It’s suitable for babies measuring 45cm to 75cm, which is essentially from birth up to 12 months. It really impressed in our tough front and side-impact crash tests, plus it’s easy to install and comfortable for your baby. The RRP is £199, but we’ve spotted it at a major high street retailer for £179.


This car seat and Isofix base has a 180-degree swivel to help you put your baby or toddler in the car seat. It’s suitable from birth up to about four years old, and it gets an excellent overall safety rating of five stars in our crash tests. It sits securely on the seat when installed and the harness works well and is very easy to adjust.

The lowest-scoring Isofix child car seats

Below are the five Isofix child car seats that have scored least well overall in our tests. We crash test every car seat we review in a front-impact and side-impact crash scenario, and our experts also do around 500 fitting checks each year to see how easy each child car seat is to fit. 

They also carry out ergonomics tests to see how comfortable your baby or child's ride will be. You can find out more details about our testing at the bottom of the page.

Lowest-scoring Isofix child car seats

Joie Every Stage FX

Test score %


The Joie Every Stage FX combination seat is identical to the Every Stage car seat we tested last year, but now has Isofix connectors added. It's still approved for use from birth up to 36kg - that's around 12 years old, or when your child may no longer need a car seat. Multi-group car seats don't always work as well as separate seats, and this seat is no different. We've named it a Don't Buy in our review because of poor crash test results in one mode. Read our safety alert for more information.

Concord Ultimax i-Size

Test score %


This child car seat and Isofix base has passed the regulatory tests required by ECE R129 to be sold as suitable for children from 40cm to 105cm. However, in our tests, which are conducted at higher speeds and forces than the standard requires, we found weaknesses in frontal-impact safety. The car seat shell broke during frontal-impact crash tests when used forward-facing. Due to this, it’s a Don’t Buy and the overall score is automatically downgraded to 20%.

How Which? finds the best and worst Isofix car seats

We crash test every child car seat we review using more severe crash test scenarios for front and side impact than the legal requirements. For example, baby car seats approved under the older car seat rules (R44.04) do not go through a side-impact crash test. 

This is why our tests find differences, and why our crash testing helps us to find the car seats that offer the best protection for your children.

Our front-crash test is equivalent to a head-on collision at around 40mph, compared with around 30mph to be approved for sale, and our side crash is equivalent to two cars crashing into each other at around 30mph. The crashes are repeated again and again, in the different ways a car seat can be used. 

State-of-the-art crash test dummies are used to test all car seats, no matter what car seat regulation the seat is claimed to be approved to. These are wired up to record the crash forces on the most vulnerable parts of the body, which our experts believe helps to accurately indicate what chances of injury a child would have in similar circumstances.

To see which impressed in our tests, go to our best car seat reviews reviews.