Head facing forward, level or tilted slightly down
Telephone headset, if needed
Top of monitor at eye level or slightly lower, about arm's length away
Document holder, if needed, close to monitor
Body upright or slightly reclined back
Shoulders and upper arms relaxed, elbows at about 90 degrees
Task lighting to reduce glare on screen n
Lumbar support for lower back
Mouse close to keyboard
Arms rest below forearms with shoulders relaxed, or remove arm rests
Wrists in line with forearms, not bent up, down or to the sides. Rest wrist just below wrists or no wrist rest. Don't rest wrists on desk.
Space between lower legs and front of seat pan
Thighs approximately parallel to the floor
Feet on floor, or on a foot rest if desk height is not adjustable
This diagrams above shoes the "natural" posture.
No posture will be comfortable for a long period of time. Periodically change positions, look away from the screen, stand and take a walk.
The best position is your next position!