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  • Writer's pictureChris Maher

Child Car Seat Installation - What Are ISOFIX anchors?

Updated: Jun 3

ISOFIX anchors refer to the metal bars situated in the vehicle seat bight where the upper and lower cushions meet. They allow for the installation of a child restraint without utilizing the vehicle seat belt system.

Car Seat Installation - ISOFIX
Isofix logo

What does it mean when a vehicle has ISOFIX?

When a vehicle is equipped with ISOFIX, it means it has lower anchors (metal bars in the seat bight where the upper and lower cushions meet) and a tether anchor to secure the child restraint to the vehicle.

Car Seat Installation - Anchor Points
Isofix anchor points in a vehicle seat

What is a tether anchor?

A tether anchor is the designated position in the vehicle where the top tether strap of the child restraint is connected. Its location varies depending on the vehicle model, as specified in the vehicle owner's manual.

Car Seat Installation - Tether Strap Anchor
Example of tether strap anchor points


What is a top tether strap?

The top tether strap is typically positioned on the upper part of the back of the child restraint. It is designed to reduce forward movement of the child's head in the event of a crash, particularly when installing a forward-facing car seat.

Car Seat Installation - Top Tether Strap Example
Example of how a top tether strap should cocoon a child

Why should I consider an ISOFIX compatible seat?

ISOFIX seats offer easier installation of child restraints, potentially increasing the likelihood of correct fitting and optimal performance during a crash. They are particularly beneficial when transitioning child restraints between compatible vehicles.



Are all child restraints ISOFIX compatible?

No, ISOFIX compatibility is an option for car manufacturers. Only rear-facing infant restraints and forward-facing child restraints, suitable for children up to approximately 4 years old, may have ISOFIX capability.


Can I install a child restraint using both ISOFIX + Top tether AND the vehicle seat belt + Top tether?

No, child seats should be installed using only one method – either the vehicle's seat belt and top tether or ISOFIX + top tether. Always refer to the child restraint user guide for guidance. Here at BabySafe&Clean, we help install child car seats.


Is it safer to use ISOFIX + top tether or the vehicle seat belt and top tether to install a car seat?

Both methods are equally safe when installed correctly. Consult the child restraint user guide and vehicle owner's manual to determine the best installation method for your vehicle and child.


Do ISOFIX seats still require the use of the top tether strap?

Yes, Australian regulations mandate the use of the top tether strap for all rearward and forward-facing child restraints, including ISOFIX compatible ones, to prevent forward rotation in a crash.


Why does Australia require the use of a top tether strap on ISOFIX seats?

Australia advocates for top tether straps due to their proven effectiveness. AS/NZS 1754 incorporates tether straps into ISOFIX compatible child restraints, enhancing safety without compromising seat design.


Can I convert my existing child car seat to an ISOFIX seat?

No, child restraints lacking connectors for ISOFIX low anchorages cannot be retrofitted. Manufacturers are prohibited from adding such connectors as per safety standards.


Will I be able to buy a strap to fit my existing child restraint to make it suitable for installation to the ISOFIX?

No, adding straps to ISOFIX low anchorages is not recommended, as it may compromise the restraint's effectiveness and safety. Manufacturers advise against such modifications.


Can aftermarket ISOFIX low anchorages be fitted in my vehicle?

No, installing aftermarket ISOFIX low anchorages is not recommended by Australian road authorities due to safety concerns.


Will I be able to fit ISOFIX compatible restraints across the back seat?

Most vehicles have only two pairs of ISOFIX low anchorages across the back seat, limiting the use of ISOFIX compatible child restraints to two. Additional anchorages may allow for a third restraint if available.


Can I use an ISOFIX compatible restraint in the front seat of my vehicle?

Most Australian states/territories prohibit children under 4 years old from sitting in the front seat. Exceptions may apply to utility vehicles. Additionally, rear-facing restraints cannot be used where an airbag is present.


Why are ISOFIX Compatible Child Restraints only available for children up to four years of age?

Australian Standard AS/NZS 1754:2013 permits ISOFIX anchors only for Type A and Type B restraints, designed for children generally under 4 years old. Larger restraints, such as Type G, for children up to 8 years old, are not compatible due to potential anchorage limitations.


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