Elements：Seat height, seat depth, seat width, seat inclination, backrest height, backrest inclination, armrest inner width, armrest height
Seat height: the height of the front edge of the seat shall be almost equal to the length of the shin. Between 380-450mm.
Seat depth: the distance from the front edge of the seat to the back edge. The depth should refer to the length of the thigh which is around 450mm.
Seat width: the distance from the left side of the seat to the right. No less than 380mm for the armless chair and no less than 460mm for the armchair. The seat width of 530mm shall meet the needs of 95% of people (Page 8 in Chapter4.1. Ergonomic design of chair).
Backrest height: the distance from the upper edge of the backrest to the junction of the back and the seat, lower than the height of the scapula. Around 460mm.
Armrest inner width: 420-440mm. No more than 10 degrees if there’s a horizontal inclination.
Armrest height: 240mm above the seat, give or take.
Conception of Sitting Comfort
The weight of thighs and upper limbs must be supported by the seat surface when people sits. There are two small round bones under the pelvis, which can support most of the weight of the upper body. The distribution of the pressure from the hip on the seating surface should be the max at the ischial tubercle, and then gradually decreases outward until the lower part of the thigh in contact with the front edge of the seating surface, where the pressure is the least.
The seating surface below the sciatic bone should be approximately horizontal so that the femur does not bear excessive compression. The funnel-shaped seating surface or the seating surface is too soft, which will make the femur tend to rotate upward and bear force, resulting in discomfort.
- Chapter5.5. Functional dimension design of chairs, “Structure Design of Chairs” by Fujian Agriculture and Forestry University on MOOC, 2021.
- Chapter4.1. Ergonomic design of chair, “Ergonomics” by Northwest A&F University on MOOC, 2020.9.