Ask if you can try out a new chair for a day before you or your company buys it. Many vendors will let you do this.
Adjustable chairs make the best office chairs, since they can accommodate most people regardless of size.
Once you have an adjustable chair – adjust it. Many people go for years without bothering to do this.
Your chair’s seat should be flat or only slightly contoured, to allow easy adjustments of posture, and wide enough to allow shifts from side to side. Also, the seat should taper downward at the front to avoid pressure on the back of the thighs.
The seat cushion should be about half an inch to an inch deep. A hard seat can hamper circulation in the legs.
Armrests are not essential, but they can ease back stress, since they allow you to shift weight to your arms. Many armrests are too high, so height-adjustable or removable ones are best.
Your chair should offer firm padding and a back support that fits the natural curve of the spine. The backrest should be neither springy nor rigid. Chairs that have a spring adjustment let you control the degree of support.
If your chair lacks a contoured backrest, a well-placed cushion could save stress on your back.
Your chair should allow your back to angle backward a few degrees to increase blood flow and reduce compression of the spine.
Leather chairs are attractive but slippery. Instead, opt for chairs covered with a nonstick fabric to prevent sliding.
Maintain good posture, whether you are sitting upright working at a computer terminal or leaning over a desk to write a memo.
Your feet should rest flat on the floor with your knees bent at a 90° angle. If necessary, get a footstool.
Be sure to fidget. No chair will keep you comfortable all day, and sitting for long periods of time is bad for your back. Change positions and get up and walk around from time to time.