For a good sitting posture, your feet are fully on the ground. Leave three to four fingers of space between the seat of your chair and the back of your knee. The low back support of your chair should be just above your waistband. Arms lie relaxed on the armrests that are approximately at elbow height.
What is a good sitting position on your desk?
Always place your screen and keyboard directly in front of you. Make sure that the top edge of your screen is completely at eye level. Keep an arm's length distance between your eyes and your screen and move your computer mouse from your forearm. Finally, place your keyboard about six inches from the edge of the table.
Adjust your backrest and elbow room if you have an adjustable chair and desk. The lumbar support extends just beyond the waistband. The armrests are at the same height as the work surface, with the shoulders in a relaxed position.
Move while sitting
Change your sitting position regularly and take a break every 20 to 30 minutes by standing up and moving. It is important to loosen and not secure your chair.
Source:gezondheid.be