by C.M. Mackenzie
There are different styles and designs of computer or office chairs. Most new models are adjusted pneumatically. Pneumatic office chairs have a lever or a button below the seat that you can push or pull to adjust the height. Older computer chair models can be adjusted by turning a thick bolt (these bolts usually have a thick plastic molded cover with finger grips). Adjusting the height of your office chair to fit your body type is very important. Back ache and pinched nerves can occur otherwise -- especially after long periods of sitting.
Place the chair in front of the desk or table where you will be sitting most often. This makes it easier to adjust the chair according to your back support and height needs.
Become familiar with the chair's adjustments. Locate the lever or button, if the chair is pneumatic, or bolt, if the chair is not pneumatic, for adjusting the height. These will usually be located directly below the seat. There may be two levers or bolts. One will be for adjusting the back support and the other for adjusting height. Models vary, and you will need to try each to discover which button adjusts the height and which button adjusts the back support.
Adjust the height. Stand in front of your chair and press the pneumatic lever (up or down, depending on the chair model) with one hand. Gently lift on the seat of the chair with the other hand. The chair seat should move slowly. Office chairs that are non-pneumatic can be moved by loosening the height-adjustment bolt by hand and pulling up or down on the seat until it is at the right height. Lock the position by re-tightening the bolt.
Test the chair's height. Carefully, sit down on the chair when it seems to be at the right height. Your feet should rest flat on the floor, with your knees lower than your waist and bent slightly wider than a right angle. If you need to, repeat step three until you can sit in your office chair in the correct position. Some chairs will automatically lock into place once you release the pneumatic lever. Others may have a separate locking mechanism. Be sure to check this before placing your full weight on the chair.
You can adjust the height of most computer chairs while you are sitting in them, but it usually causes less wear on the chair if you adjust it up or down with little or no weight on it.
Computer chairs will last longer if they are treated with care, so do not raise and lower them more frequently than necessary.