The depth of a seat is important for both comfort and health. This applies to adults as well as children.

A basic principle of ergonomics is that seat depth should always be designed around the smallest users. A seat that is slightly too short is preferable to one that is too deep, as illustrated in the image.

What is the right seat depth for children?

Who are the smallest users of pushchairs and children’s chairs? Babies should only use a seated position once they are able to sit upright independently and steadily. On average, this is around the age of nine months. The smallest users are therefore the smallest nine-month-old children. For these children, the distance from the back of the buttocks to the back of the knee is approximately 14 cm. To prevent the edge of the seat from pressing into the back of the knee, the seat should therefore be no more than around 13 cm deep. Children’s chairs often take the dimensions of smaller children into account. With most pushchairs, however, the seat depth is almost twice as great, meaning children may not fit the seat properly until they are over three years old.

Advice

So what can you do if you want children under the age of three to sit comfortably and in an ergonomically healthy position? If a seat is too deep for a child, place a firm piece of foam or a cardboard box of the appropriate dimensions between the child’s back and the backrest. This effectively reduces the seat depth and provides a temporary solution. I would recommend sharing this practical tip with parents. I also recommend my book, Geef je baby de ruimte! en andere tips voor babyproducten (‘Give Your Baby Space! and Other Tips for Baby Products’), which contains more information that parents will find useful. In the longer term, I hope designers and manufacturers will adapt the dimensions of their seats more effectively to accommodate smaller children. After all, don’t we all want to create the best possible products for babies?

Brecht Daams is an independent ergonomics consultant (ergonomie.nl) and a member of the NEN standards committee for childcare articles. She studied Industrial Design Engineering at Delft University of Technology. As a specialist in baby ergonomics and a mother of three, she writes columns on the ergonomics of baby and children’s products.