Are You Sitting Comfortably? Guidelines for Comfortable Seat

Is your office chair comfortable enough? Here is a formula for comfortable seating: create a right angle, open it up a tad, and tip it backward, so that our bottom can be placed in a position lower than that of knees. Our weight is thrown back into the angle and our thighs lock our back firmly into the backrest.

Is there such chair that can keep us comfortable for hours, even though we all know prolonged sitting in the chair is bad? Is there any such chair that can ensure the maximum comfort to each individual? Anyway, this is a question for the chair designer. For catering to each user, there is a need to adjust the dimensions and angles slightly based on each individual body shape or size. For such a chair that guarantees the comfort to the individual, there is a lot of factors in aspects of the dimensions and angles of the chair. Here are some essential guidelines for chair design, especially the must-have measures in the design of seat, back, armrest and angles, which especially apply to an average-size 5' 10" adult sitting in an upright position.

As for the seat, in order to allow those seated in the chair to rest the feet just flat on the floor with a knee angle between 90°and 100°, there is a need to locate the seat 16–18" above the floor. The chair designer also needs to take into consideration the thickness of any possibly used cushion on the chair. Just subtract half the cushion's thickness.

The seat has to be designed to be 15–18" deep so as to allow the clearance between the seat's front edge and the legs of the chair user.

Besides, the width of the chair needs to be around 16–20". Of course, we can adjust it based on our own need and the specific chair’s style by 2–3" from front to back. If the front of the seat can be wider, there will be more room for leg yet if the back of the seat is narrower, there will be little room for elbow.

If the chair we sit on has no cushion, we can slope it 5–8° from front to back. In this way, we can slide forward for extra comfort. If the chair is for office use, then just ignore this because a flat chair can help us lean forward.

As for the back of the chair, if we want the chair to offer us lower-back support yet not to interfere with our shoulders, the back height of the chair should be 12–16" above the seat or 20" which is very common for the chair we use. If the chair we use is office chair, just try to slant its back up to 5°and 15° for a casual chair. Anyway, when we increases the back angle, we need to keep the  seat-to-back angle between 90° and 100°so as to avoid forward sliding. Besides, we still need to lower the seat height to keep the front edge of the seat from contacting the back of the legs.

Finally, we need to position the armrest 7–9" above the seat so it can support our forearms and still will not interfere with our shoulders.