Ergonomic chairs are designed to be adaptable to the user's needs and are associated with higher productivity levels due to the customized support that they offer. Typically office chairs are classified as ergonomic when they have an adjustable seat height, seat depth and lumbar support. This means that you should be able to adjust the height of the chair so that your legs are perpendicular to the floor and the seat pan should allow you to adjust it so that you're able to sit comfortably.