How to Measure for a Desk Chair

Sit in the chair, and pull it up to your desk. Adjust the chair height -- and armrests, if present -- until your elbows form a 90-degree angle when you are sitting straight up, resting your hands naturally on the keyboard or desk.

Place both feet flat on the floor while you are sitting in the chair. Slide your fingers between your thighs and the chair. If you don't feel about one finger's width of space between your thighs and the chair, prop your feet up with a box or ergonomic footrest. If you lower the chair, the 90-degree angle formed by your arms changes, so adding a footrest is the best option. If you are unusually tall, and feel more than the finger's width of space between your thighs and the chair, raise the chair until it fits properly, increasing the height of your desk or workspace if necessary.

Place a closed fist between the chair and the pit behind your knee. If you cannot fit your fist in this space, you are sitting too far back. Place a backrest behind you or choose a chair that isn't as deep from the front to the back of the seat.

Close your eyes while you are sitting in the chair, and then open them slowly, while looking straight ahead. Adjust the monitor height until you look directly at the middle of the screen without moving your head up or down, and then move the monitor forward or back until it is between 20 and 40 inches from your eyes.

Check the width of the seat while you're sitting in it. If you have to squeeze in, the chair is too small. The standard 17- to 22-inch seat width accommodates most people, but if you don't fit in this range, choose a chair that fits your body.