i-Size Car Seats

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For Your Little One AllStage 360 0/1/2/3 ISOFIX I - Size Car Seat - Slate Mist (Birth - 12 Years) - For Your Little One For Your Little One AllStage 360 0/1/2/3 ISOFIX I - Size Car Seat - Slate Mist (Birth - 12 Years) - For Your Little One

For Your Little One

For Your Little One AllStage 360 0/1/2/3 ISOFIX I-Size Car Seat - Slate Mist (Birth-12 Years)

£79.99
£79.99 -46%
£149.99
(84 reviews)
For Your Little One AllStage 360 0/1/2/3 ISOFIX I - Size Car Seat - Midnight Black (Birth - 12 Years) - For Your Little One For Your Little One AllStage 360 0/1/2/3 ISOFIX I - Size Car Seat - Midnight Black (Birth - 12 Years) - For Your Little One

For Your Little One

For Your Little One AllStage 360 0/1/2/3 ISOFIX I-Size Car Seat - Midnight Black (Birth-12 Years)

£79.99
£79.99 -46%
£149.99
(123 reviews)
For Your Little One AllStage 360 0/1/2/3 ISOFIX I - Size Car Seat - Blush Rose (Birth - 12 Years) - For Your Little One For Your Little One AllStage 360 0/1/2/3 ISOFIX I - Size Car Seat - Blush Rose (Birth - 12 Years) - For Your Little One

For Your Little One

For Your Little One AllStage 360 0/1/2/3 ISOFIX I-Size Car Seat - Blush Rose (Birth-12 Years)

£79.99
£79.99 -46%
£149.99
(63 reviews)
For Your Little One AllStage 360 0/1/2/3 ISOFIX I - Size Car Seat - Sage Teal (Birth - 12 Years) - For Your Little One For Your Little One AllStage 360 0/1/2/3 ISOFIX I - Size Car Seat - Sage Teal (Birth - 12 Years) - For Your Little One
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For Your Little One

For Your Little One AllStage 360 0/1/2/3 ISOFIX I-Size Car Seat - Sage Teal (Birth-12 Years)

£79.99
£79.99 -46%
£149.99
(26 reviews)
Car Seat Group 0+ Birth to 15 Months i - Size infant car seat - pebble sage - Clearance - For Your Little One
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For Your Little One

Car Seat Group 0+ Birth to 15 Months i-Size infant car seat-pebble sage-Clearance

£35.00
£35.00
(1 reviews)
For Your Little One AllStage 360 0/1/2/3 ISOFIX I - Size Car Seat - Blush Rose (Birth - 12 Years) - For Your Little One For Your Little One AllStage 360 0/1/2/3 ISOFIX I - Size Car Seat - Blush Rose (Birth - 12 Years) - For Your Little One
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For Your Little One

For Your Little One AllStage 360 0/1/2/3 ISOFIX I-Size Car Seat - Blush Rose-Damaged box

£75.00
£75.00 -49%
£149.99
(No reviews)
For Your Little One AllStage 360 0/1/2/3 ISOFIX I - Size Car Seat - Midnight Black (Birth - 12 Years) - For Your Little One For Your Little One AllStage 360 0/1/2/3 ISOFIX I - Size Car Seat - Midnight Black (Birth - 12 Years) - For Your Little One
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For Your Little One

For Your Little One AllStage 360 0/1/2/3 ISOFIX I-Size Car Seat - Midnight Black-Damaged box

£75.00
£75.00 -49%
£149.99
(No reviews)
Car Seat Group 0+ Birth to 15 Months i-Size infant car seat-Black-Clearance
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For Your Little One

Car Seat Group 0+ Birth to 15 Months i-Size infant car seat-Black-Clearance

£35.00
£35.00
(No reviews)
Egg Shell I - Size Newborn Car Seat - Carbonite - For Your Little One

Egg

Egg Shell I-Size Newborn Car Seat - Carbonite

£148.50
£148.50 -25%
£199.00
(No reviews)
For Your Little One AllStage 360 0/1/2/3 ISOFIX I-Size Car Seat - Latte Beige (Birth-12 Years) For Your Little One AllStage 360 0/1/2/3 ISOFIX I-Size Car Seat - Latte Beige (Birth-12 Years)

For Your Little One

For Your Little One AllStage 360 0/1/2/3 ISOFIX I-Size Car Seat - Latte Beige (Birth-12 Years)

£79.99
£79.99 -46%
£149.99
(No reviews)
Car Seat Group 0+ Birth to 15 Months i-Size infant car seat-Dune Beige-Clearance
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For Your Little One

Car Seat Group 0+ Birth to 15 Months i-Size infant car seat-Dune Beige-Clearance

£35.00
£35.00
(No reviews)
Egg Shell I - Size Newborn Car Seat - Houndstooth Almond Mega Clearance - For Your Little One

Egg

Egg Shell I-Size Newborn Car Seat - Houndstooth Almond Mega Clearance

£145.00
£145.00 -27%
£199.00
(No reviews)
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i-Size Car Seats - For Your Little One i-Size Car Seats - For Your Little One

i-Size Car Seats

i-Size Car Seats – The Safest Standard for Every Stage

Shop our range of i-Size (R129) car seats – the latest and most stringent European car seat safety standard, offering significantly improved protection over the older Group system. All i-Size car seats in our range are ISOFIX compatible and meet the current UK and European R129 regulation. Free UK delivery available.

What Is i-Size?

i-Size (also known as R129) is the newer European car seat safety regulation that replaced the older ECE R44 Group system. Key improvements over the older standard include:

  • Height-based classification – i-Size seats are classified by your child's height rather than weight, making it easier to know when your child has outgrown a seat.
  • Mandatory rear-facing until 15 months – All i-Size seats must keep children rear-facing until at least 15 months, significantly improving safety for young children.
  • Enhanced side-impact testing – i-Size seats must pass more rigorous side-impact crash tests than older Group seats.
  • ISOFIX required – All i-Size seats must use ISOFIX installation, providing a rigid, secure connection to the car.

i-Size vs Group Car Seats – Which Is Safer?

i-Size is the safer standard. The mandatory rear-facing requirement until 15 months, enhanced side-impact testing, and compulsory ISOFIX installation all provide measurably better protection than the older Group system. If you're buying a new car seat, choose i-Size where possible.

i-Size Car Seats by Stage

  • Birth to 15 months (40–83cm) – Infant i-Size seats. Rear-facing from birth. Examples: Cybex Cloud T, Doona i.
  • Birth to 4 years (40–105cm) – Combination i-Size seats. Extended rear-facing. Examples: My Babiie spin seats.
  • 15 months to 12 years (76–150cm) – Toddler and child i-Size seats. Forward-facing from 15 months.

Why Choose Our i-Size Car Seats?

  • Latest R129 safety standard – The most stringent car seat regulation available
  • Mandatory rear-facing to 15 months – Maximum protection for young children
  • Enhanced side-impact protection – Rigorously tested beyond older standards
  • ISOFIX installation – Rigid, secure connection to your car
  • Height-based sizing – Easy to know when your child has outgrown the seat

Complete Your Car Seat Setup

Browse our ISOFIX bases, car seat footmuffs, car seat raincovers, and our full car seat types guide.

Frequently Asked Questions

An i-Size car seat (also known as R129) is a car seat that meets the latest European safety regulation, which replaced the older ECE R44 Group system. i-Size seats are classified by your child's height rather than weight, must keep children rear-facing until at least 15 months, must use ISOFIX installation, and must pass more rigorous side-impact crash tests than older Group seats. i-Size is the safer standard – if you're buying a new car seat, choose i-Size where possible.

Yes – i-Size (R129) is the safer standard. The key improvements over the older Group (ECE R44) system are: mandatory rear-facing until at least 15 months (significantly safer for young children), enhanced side-impact testing, compulsory ISOFIX installation (safer and more convenient than seatbelt installation), and height-based classification (easier to know when your child has outgrown the seat). Both standards are legal in the UK, but i-Size provides measurably better protection.

All i-Size car seats require ISOFIX installation – this is a mandatory requirement of the R129 regulation. Some i-Size seats have built-in ISOFIX connectors that attach directly to your car's ISOFIX anchor points; others require a separate ISOFIX base that the car seat clicks into. An ISOFIX base provides a more rigid, secure installation and makes it easier to transfer the car seat between cars. Check whether an ISOFIX base is included with your chosen seat or needs to be purchased separately.