Understanding safety and legal bits when it comes to car seats is all well and good. But what about all those fancy-fandagled words that the manufacturers and legal bods like to throw in there? It’s like saying to your average Jo (that’s me by the way! haha!) “here, we’ll tell you how it is in the most complicated way we can!” It’s tough enough being a parent and following what is best, without being continually confused by the ever changing language of car seats and safety. So let’s clear up some lingo once and for all.

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I Size

WTF is: i-Size?

Height-based, side protected and rear-facing (upto a certain age). This is the basis of the regulation designed to make car seats safer, easier to fit and updates the old law from the 80’s.


i-Size was introduced in the UK in 2013. It legally requires car seats to ensure side impact protection, which the current regulation (the 80’s one) does not. It also requires ISOFix fittings, which are safer and easier to install. I-Size has requirement for rear facing for longer (keeping your kid backwards because it’s safer than forwards in an impact) and height measured seating which is less confusing!


Image and information courtesy of good egg safety


Swedish research found that rear-facing car seats can offer up to 75% more protection if your child is involved in a car accident. Also 25% of road collisions in Europe involve a side impact, so the risk is very real, but not currently accounted for in the safety regulations from the 80’s. Things have come a loooooonnnnnngggggg way since then!



i-Size don’t fit all cars yet and when it was introduced in 2013, there weren’t many cars around in the UK that were compatible. This has changed and will keep changing dramatically in the coming years as the old regulation is phased out and the new one takes over as being “the standard”. Made For Mumshas a brilliant article on this, which was recently updated and provides a manufacturer fitting list for existing car seat companies. I’ve linked the article here for you to look at after 🙂



WTF is: ISOFix

the bits that attaches a child seat to the car. An alternative to securing the child seat with the seat belt, which, lets face it, is a pain in the arse and hard to get right!

image courtesy of Which.co.uk


ISOFix is an international standard so all manufacturers make the fitting in the same way. The idea is that the standard enables car and seat manufacturers to make compliant child safety seats across the board. It makes it quick and safely secured across all models and for all budgets. It also means that seats are much more likely (up to 75% more likely!) to be fitted correctly and therefore in the safety possible way for your tiny person.


ISOFix can reduce the risk of incorrectly installing which, believe it or not, is actually the biggest safety problem around car seat  use. Madeformums state that “evidence suggests that up to 75% of car seats are not fitted correctly.” They add “According to car seat manufacturer Maxi-Cosi, safety tests found 94% of parents use ISOFix correctly, while only 20% of parents install car seats correctly when using a seat belt.” Scary stuff!


ECE Regulation 129

WTF is: ECE Regulation 129?

This is just the name they come up with for a NEW regulation that is running alongside, not replacing, the old car seat regulation (sort of law) The old one was first made in the 80’s.


ECE 129 will eventually replace the current regulation (ECE Regulation 44/04) but not yet.


Like we’ve said earlier, the original regulation has been around since the 80’s and isn’t really fit for purpose anymore. Our learning about cars and collisions, as well as huge leaps in technology means that the regulations need to keep up. The old regulation is still in force but will be phased out slowly over time.

Both pieces of legislation will continue to run alongside each other . There has been no date set, as yet, to when the new legislation will take over but, even when it does, it is likely that a transition period will be set so seats can be changed at an affordable rate and panic buying doesn’t ensue!


So What are you saying Pud?

Take Away Points from the regulations and info above:

  • Your child must sit in a car seatuntil they are 12 years old or 4’5” tall, period.
  • With I-Size, if a child is less than 15 months old (this used to be 9 months) they can, and should, be rear facing​​
  • When choosing a seat, make sure you pick one that will be secure: You’re more likely to fit it correctly if you get ISOFix – so I’d plump for that.
  • All car seatsin the UK must be EU-approved so check yours is marked with an E.


How to fit a child car seat correctly


  • Deactivate any front-facing airbags if you’re using a rear-facing seat.
  • Check the seatis secure and won’t wiggle around.
  • Ensure the seat buckle is outside the frame (there’s a risk it could come open in an accident otherwise).
  • If you’re fitting a seat for a baby, make sure the harness is pulled tight with a maximum of two fingers’ room between their collar-bones and the shoulder straps.
  • Take bulky coats off and pop them a blanket OVER THE TOP of their seat belt or harness. This means there is less chance of the belt being too loose and not being able to do its job.
  • Check the harness buckle is as low as possible – ideally across the child’s pelvis rather than their stomach.
  • Make sure everything is adjusted in line with the seat’s


Still unsure or want to buy a new seatWhich has tested them for you here ​

For a chuckle and brilliant info, watch this video from besafe.com

What are your seat plans now? Is there any other lingo that throws you into confusion? Let me know!