Legs -- Chair should have 5 legs for stability and appropriate casters for easy movement while seated.

Height -- Seat height should be pneumatically adjustable while seated. A range of 15-21 inches off the floor should accommodate most users. Thighs should be horizontal, lower legs vertical, feet flat on the floor or on footrest. Seat height should also allow a 90 degree angle at the elbows for typing.

Seat -- A seat width of 17-20 inches suffices for most people and should be deep enough to permit the back to contact the lumbar backrest without cutting into the backs of knees. The front edge should be rounded and padded. The seat slant should be adjustable (0 to 10 degrees). Avoid bucket-type seats. The seat should swivel easily.

Backrest -- The backrest should offer firm support, especially in the lumbar (lower back) region, should be 12-19 inches wide, and should be easily adjustable both in angle and height, while sitting. The optimum angle between seat and back should permit a working posture of at least 90 degrees between the spine and thighs. Seat pan angle and backrest height and angle should be coordinated to allow for the most comfortable weight load on the spinal column.

Padding -- A chair seat and back should be padded enough to allow comfortable circulation. If a seat is too soft, the muscles must always adjust to maintain a steady posture, causing strain and fatigue. The seat fabric should "breathe" to allow air circulation through clothes to the skin.

Armrests -- Armrests are optional, depending on user preference and tasks performed. They should not restrict movement or impede the worker's ability to get close enough to the work surface. The typist should not rest his or her forearms on armrests while typing.

What to Look for in a Good Ergonomic Chair