How to Buy the Right Car Seat for Your Car

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How to Buy the Right Car Seat for Your Car

Selecting the correct car seat for a particular car involves more than identifying the right sized seat for that vehicle. It starts with identifying the right seat group for the child or children. Car seats are most often fitted to the rear seats of vehicles because of passenger side airbags that could injure a child in an accident. In older vehicles without airbags, it is still legal for the child to ride in the front. Some new vehicles have ISOFIX attachments in the rear seat for infant and toddler seats. If the vehicle has these secure attachments, which meet new international safety standards, then a child seat that takes advantage is well considered.

The shape of a specific vehicle seat can make a specific child car seat fit more or less well, as can the safety belt configuration if that is the attachment device. When purchasing a child car seat, it is wise to check any manufacturer information about what vehicles can fit. It is also helpful to select a vendor that offers returns should there prove to be a difficulty with fit in the vehicle where it is typically used. Car seats purchased on eBay may be selected from a wide range of vendors across the UK, many of which offer returns or even ask that car seat purchasers collect their seat in person. Either option gives the buyer the opportunity to confirm the fit and make sure they have the right seat for their car.

Car Seat Sizes

Car seats are sized to fit children according to their weight, which generally corresponds approximately to their age. Car seats for smaller children often have features associated with infant transport systems, such as the ability to lock into a pushchair. Some car seats are made in "combination group" sizes designed to allow children of different ages to safely use them. The chart below summarises car seat sizes and any associated special features that may be available.

Seat Group

Retail Name

Child Size and Age

Features and Value

Group 0

Stage 1

Up to 10 kg or about 6 months

No longer produced; existing seats may still be in the market

Group 0

Stage 1

Up to 13 kg or about 12 months

May have a handle for carrying when removed from car system; some snap into pushchairs; alone, may be set into supermarket trolley basket or used as baby rocker in home

Group 1

Stage 2

From 9 - 18 kg or 9 months to 4 years

May be fastened in the car facing rearward for younger children then forward facing when child attains 9 kg or is able to sit unaided; often have adjustments for reclining

Group 2-3

Stage 3
Stage 4

From 15 - 36 kg or 4 years to 12 years

Front facing seats

Group 0 /1

Stage 1-2

Up to 18 kg or about 4 years

Adjustable to be used over the child's growth or to be used with several children

Group 1-2-3

Stage 2-4

From 9 to 36 kg or about 9 months to 12 years

Adjustable to be used over the child's growth or to be used with several children

Manufacturers are producing more combination group seats than single stage seats for many reasons. A major reason is that they may be sold to a wide variety of households, not just households with a child in a particular growth stage. This provides significant economies to families by being able to continue using the same seat over time.

Types of Car Seats

The three broad categories of car seats are the rear-facing infant seat, forward-facing child seat, and the booster seat or cushion for older children. In older cars, the seats are attached using the vehicle's seat belts. Some newer cars have the ISOFIX or ISOFIT systems, which are the safety standards for attachment of child safety seats.

Rear-Facing Infant Seat

Rear-facing car seats, designed to protect the neck, head, and spine of a small child, are typically used for children under 15 months. They are used in the back seat of the vehicle only when there is a passenger air bag in the front. They have their own harness system, which includes shoulder straps and a strap between the legs.

Forward-Facing Child Seat

Forward-facing car seats are used for children from 9 to 18 kg or approximately 9 months to 4 years old. They are designed with their own harness system, which includes a strap between the legs to help keep the child from sliding out of the chair. These seats are safest when used in the rear seat of the car and should never be used in the front seat if there is a passenger airbag in front.

Booster Seats and Cushions

Booster seats and cushions are designed for children in Groups 2-3. Contemporary booster seats and cushions are typically combination seats made for children throughout this weight range. Some have wings to protect a child in a side collision. These seats do not have their own harness system. The vehicle's passenger harness holds the child in place and doing so also holds the seat in place.

ISOFIX and ISOFIT: The Safety Standards for Car Seat Attachments

Although Group 2-3 seats do not have their own harness systems, in recent years new safety systems have been developed to attach the seats themselves to the vehicle seat. These systems, called ISOFIT, derived from the earlier ISOFIX systems developed in the late 1990s for Group 0/0 and Group 1 car seats.

ISOFIX attachments are a three-point attachment system manufactured into the automobile seat. By holding the child seat to the vehicle seat, the child seat is not thrown forward in the event of any sudden deceleration as it may be when fastened by straps. This better protects the child from injury. ISOFIX is ISO 13216 of the International Standards Organisation and has been required since the early 2000s.

Specific Concerns About Car Seats

Other issues to consider in selecting the right car seat include the proper fit of the car seat to the specific vehicle or vehicles being used. It is important to know how easily the car seat is attached securely in place. Different families may have different priorities as to whether a seat that is part of an infant transport system is desirable, or perhaps a multistage seat that may be used as the child grows.

Fitting the Car Seat to the Vehicle

Several issues pop up with regularity as parents attempt to fit car seats to their vehicles. The chart below summarises some of these challenges along with the initial steps that may be taken to resolve them.


Initial Steps to Resolve

If Unsuccessful

Seat belt does not tightly hold child seat

Check instructions; confirm correct seat belt routing; tighten; confirm seat is set tightly on car seat; confirm car seat is suited to vehicle.

Replace car seat.

Seat belt does not reach around child seat

Try alternative belt routings; adjust belt height on the door pillar if possible; if using front seat, move seat further back; try other locations in car for possible better fit; confirm that child seat is suitable to vehicle.

Replace car seat.

Seat belt buckle lies on child seat frame

Try alternative belt routings; try other locations in car for possible better fit; confirm that child seat is suitable to vehicle.

Replace car seat.

A seat belt buckle that lies on the child seat frame poses a risk because of the additional strain that could be placed on the buckle during sudden deceleration. The buckle may be more likely to unfasten under pressure from the child seat, allowing the seat to be thrown forward. For safety, only the webbing of the belt should lie across the child seat frame.

Using a Baby Car Seat in More Than One Vehicle

If a grandparent or childminder also plans to use the car seat, make sure it fits their car or cars. If more than one car is used on a regular basis, it is often advisable buy a seat for each so there is always a seat in the car that is about to be taken out.

Ease of Attachment and Removal

Child car seats that are difficult to attach properly are frequently attached improperly. One study by the German Insurance Institute GDV found nearly 7 in 10 children's car seats incorrectly attached. An incorrectly attached seat puts the child at risk in an accident and may even put at risk a particularly energetic child. It is wise to find a car seat that is simple to fasten correctly into place.

Infant Transport System

Infant transport systems are convenient for moving very small children from the car to the pushchair to the shopping basket and back again. Many parents find that once a child has grown past about six months that the child becomes too heavy for easy lifting, making these kinds of systems rather short term solutions.

Pluses and Minuses of Multistage Seats

Multistage seats are designed to allow the same child car seat to be used for an extended period. In the case of the Group 2-3 seats, a booster chair may be designed with a removable booster cushion so that the same device that provides for a 4 year old continues to serve the same child up to 36 kg.

The limitation of the multistage booster seat is that it has no restraint system of its own but relies on the passenger harness system of the vehicle. It is important to use caution to ensure that the shoulder belt does not wrap the neck and the lap belt lies across the pelvic region, not the stomach.

Determining When a New Car Seat Is Needed

Several guidelines are offered for determining when it is time for a child to graduate to a larger car seat. It is typically time to move up to the next seat under any of the following conditions: the child's weight exceeds the weight limit of the seat; the child's eye line is higher than the seat's highest point; or a child in a Group 0 chair sit ups unaided on a regular basis. It should be noted that children must be in rearward facing seats until they weigh 10 kg if using a Group 0 seat and 13 kg for a Group 0 seat, according to regulation ECE44.

Concerns with Second-Hand Seats

Many sources advise against purchasing a second-hand car seat or even using a seat that has belonged to a friend or relation. The concerns repeatedly offered are that the seat may not meet current safety standards and the seat may have been damaged in a motor vehicle accident in such a way that the damage is not immediately evident.

If considering a used car seat from a friend or relation, consider the age of the seat,, whether the instructions are available, and whether you are certain of its history. Any car seat to be used should meet the current United Nations standard Regulation 44.03 or 44.04, which is be indicated by an "E" mark.

Buying the Right Car Seat on eBay

On eBay, you can find a great many child car seats offered for children of all ages and sizes. As is true in the market as a whole, many are multi-stage seats that can grow with the child. Still, it is important to identify a child seat that correctly fits the vehicle in which it is to be used. The owner's manual or other information from the manufacturer is likely to indicate which types of vehicles a particular seat is designed to fit properly. If you have any questions about a particular seat, you may ask the seller for information. You can also find a Q&A tab where you may pose this and any other questions to the seller on the product page.

Check the Returns Policy

In case a seat cannot properly fit your vehicle, it is important that you are able to return it. When reviewing the seller's policies on the postage and payments tab of the product page, check whether returns are accepted and under what conditions. Sellers who offer car seats for "collection only" also are likely to give the buyer an opportunity to try the seat immediately before taking it. Buyers closest to your location may be identified by using the sort menu to find those closest.


Car seats are not entirely standardised making the selection of the right car seat for a particular vehicle a bit of an art. Car seat design has changed over the last decade, most notably with the introduction of the ISOFIX and ISOFIT attachment systems starting in the late 1990's. Seats with these systems fit cars with these systems. There is still some variation among models, so it is important to confirm that the car seat model chosen is designed to be mounted in the vehicle being driven. For car seats using a traditional seat belt attachment, the same is true: Different models fit differently into different vehicles. The curve of a vehicle seat or length of a seat belt can make a particular car seat fit differently in different vehicles.

When buying a car seat on eBay, there are two ways to help ensure the proper fit. One is to confirm that a seller allows for returns if the fit proves incorrect. The other is to shop from a seller who requires collection of the chosen car seat. In that way, the buyer may immediately test whether the seat fits properly and if not, immediately return it. Taking the aforementioned factors into consideration ensures that buyers purchase the right car seat.

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