Office Chair Ergonomic Dimensions

Office chair ergonomic dimensions involve multiple aspects such as seat height, seat depth and width, backrest parameters, tilt and armrests, as well as other parameters. The specific specifications are as follows:

1. Seat Height: According to the national standard GB 3326-1997, the conventional seat height is 400-440mm (with a grade difference of 10mm), and can be extended to 40-55cm in office settings. The calculation method is seat height = height from the back of the calf to the sole of the foot + heel thickness - activity allowance (usually 5-10mm). An appropriate seat height ensures that the user's feet can rest flat on the ground, with the thighs parallel to the ground, reducing leg pressure.
2. Seat Depth and Width: The seat depth ranges from 380-420mm, ensuring that there is a 60mm buffer space between the front edge of the seat and the back of the knee to avoid compressing the back of the knee and affecting blood circulation. In terms of seat width, the minimum width of a single-person chair is 380mm. For chairs with armrests, additional allowance should be added according to shoulder width (450mm for men/400mm for women), and the inner width of the armrests should reach 350-480mm. Another view states that the dimension from the front to the back of the seat should be 406mm, and the chair width should be 406-560mm.
3. Backrest Parameters: In terms of height matching, 480-630mm covers the height from the bottom of the buttocks to the shoulders. The lumbar support point should correspond to the position of the second and third lumbar vertebrae (about 180-250mm above the seat surface). Another view states that the backrest height should be 635mm to support the shoulders, 915mm when head support is needed, and 400mm when the hands can reach the back. The width is designed to be 350-480mm to accommodate shoulder movement, and an upper-wide and lower-narrow shape can reduce scapular compression. The backrest cushion is curved and made of soft material 25-51mm thick to prevent swaying to the sides, with an arc radius of 1000mm being more appropriate.
4. Tilt and Armrests: The seat surface tilts 3-5° backward in conjunction with the synchronous tilt of the backrest, forming a 100-110° seat-back angle, which can disperse buttock pressure. Another view states that the horizontal adjustment angle of the seat surface is 0°-15°, and the adjustment angle of the backrest is 0°-15°. The armrest height is a vertical height of 200-250mm (measured from the seat surface), which should match the height of the elbow when hanging down. For tilted armrests, it is recommended that the front be higher than the back, with an angle not exceeding 20°. The armrest spacing is 483mm, the armrest width is 51mm-89mm, the armrest length is 254mm forward from the seat reference point, and 305mm when not working at a desk.
5. Other Parameters: The seat cushion is made of soft material with a thickness of 51mm and has no bottom plate. There should be no backrest within 76mm above the seat surface, as this space is reserved for the buttocks. The radius of the rounded edges of the front edge of the seat surface and the lower edge of the backrest is 12.7mm. The chair should be able to rotate and should have 5 or 6 legs for stability.