1, the seat height refers to the vertical distance from the seat surface to the ground; If the seat surface is inclined backward or concave arc, the seat height refers to the vertical distance from the center of the front edge of the seat to the ground. If the seat height is too high, the legs will be suspended and the thigh blood vessels will be oppressed; Too low will cause physical fatigue.

2. Practice has proved that the appropriate seat height is the height from the calf socket to the sole plus the heel thickness of 25-35mm, and then minus the activity margin 10-20mm. Namely: seat height H = calf socket height+heel thickness-appropriate clearance.

3. The national standard GB 3326- 1997 stipulates that the seat height H is 400-440mm and the size difference is 10mm. The maximum height of the soft seat surface is 460mm (excluding the subsidence of the seat surface). The height of the sofa seat can be lower, so that the legs extend forward and lean back, which is beneficial to the natural state of the spine. The height of the sofa is generally 360-420mm.

Second, the size standard of the seat depth of the chair.

1, the seat depth refers to the distance from the front edge to the rear edge of the seat. Too deep and too shallow will make the calf and back tired and uncomfortable. Practice has proved that the sitting depth should be slightly less than the horizontal length of thigh when sitting. That is, the sitting depth T= the horizontal length of sitting thigh exceeds 60mm (gap).

2. The national standard GB 3326- 1997 stipulates that the seat depth T is 340-420mm (armchair) or 400-440mm (folding chair), and the size difference is 10mm. Leisure seats such as sofas can be slightly deeper, 480-560mm, because the backrest is inclined.