CORRECT CHAIR DESIGN 

A computer task chair would ideally contain the following features: 

• Adjustable height seat
• Adjustable height arm rests.  (the mechanism should be easy to use)
• Adjustable forward tilt of the seat pan (the part you sit on)  minimum 10 degrees
• A straight firm adjustable height backrest with some additional support for the lumbar spine.  The angle of the backrest should adjust independent of the angle of the seat pan. 

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  Since people come in all sizes, there will not be one chair that perfectly accommodates all employees.  Providing two types of chairs, one suited to a larger body build (longer seat pan, wider seat pan, arm rests further apart, higher back rest) and another better suited to a smaller body build (shorter seat pan, narrow seat pan, arm rests closer together) is a good way to accommodate the majority of employees.  A chair fitting this basis design can be retrofitted with a few small items to get a more exact fit for the majority of employees.   

  Fitting a chair:

  • Feet sit flat on the floor on a footrest.
  • The seat pan (part you sit on) should be long enough to support the thighs but should not be so long that there is pressure against the inside of the knees.  Try sitting way back in the chair.  There should be a few inches between the back of the knees and the edge of the chair.
  • The arm rests should be fairly sung so you don’t have to bring the elbows more then a few inches away from the body in order to rest the elbows on the arm rest.  (Note: If the desk set-up allows resting the arms comfortably on the surface of the desk, arm rests may not be needed)
  • The back rest should be contoured to allow proper spinal alignment.  Sit back as far as you can and rest you back against the back of the chair.  Have someone look at you from the side.  Three points (ear shoulder and hip) should form a straight line.
  • Forward tilt of the seat pan (see above) allows the knees to rest slightly lower than the hips. 

  Wendy Richardson, P.T.