Buying an office chair online saves money, but you lose the chance to sit in it. If you have not tried the model in person, the specifications are all you have, and the most important ones are the seat height range and the seat depth. The trick is knowing your own numbers first.
Measure yourself
Sit on a hard chair or stool with your feet flat on the floor and your thighs roughly level. Measure from the floor to the back of your knee, the crease behind it. That is close to the seat height you want, often adjusted down an inch or so if you wear thicker shoes at work. Most adults land somewhere between about 16 and 21 inches.
While seated, measure from the back of your hips to the back of your knee. Subtract two or three inches and you have a rough maximum for seat depth, enough to leave a few fingers’ gap behind the knee.
Read the specifications
Check that your seat height sits comfortably inside the chair’s range, not at either end. If you are near the bottom of the range and still dangling, the chair is too tall for you. Many manufacturers sell shorter or taller gas cylinders for the same chair, which is worth knowing if you are under about five foot four or over six foot two.
Then check the desk. Once your seat is right, your elbows should be at roughly desk height with shoulders relaxed. If the desk is too high, raise the chair and add a footrest. If it is too low, consider desk risers or an adjustable desk.
Arm height and width
Look for armrest height that can come down low enough to let your shoulders drop, and a width that keeps your elbows near your sides. If your measurements fall between sizes, prioritize seat height and depth. Arms can be adjusted or removed; a seat that is too deep cannot.
When you have several users
Shared desks and shift work make adjustability more important than any single number. Wide height ranges, a sliding seat and easy-to-find levers will save you more complaints than any premium fabric. For the rest of the checklist, see what to look for in an office chair.
Sources: Computer Workstations eTool: Chairs, OSHA; Ergonomics and Musculoskeletal Disorders, NIOSH.
