When choosing and adjusting your chair, consider these factors:

• Ensure adjustment controls are easy to use while seated.
• Check the load rating to match your body weight.
• Look for a backrest with adjustable lumbar support to fit your lower back curve.
• Opt for a backrest that tilts forwards and backwards.
• Choose a well-cushioned chair that supports most of your thigh length and body width.
• Adjust seat height and tilt for comfort.
• Look for a seat with a rounded front edge and a five-point caster base.

Armrests can be beneficial for forearm support or assisting with getting in and out of the chair. Ensure they are removable and adjustable to allow for proper desk positioning.

When adjusting your chair:

• Set the chair height so your elbows are level with the desk for forearm support.
• Use a footrest if needed.
• Adjust the backrest height to support your lower back curve.
• Ensure clearance behind your knees for leg movement.
• Tilt the backrest to a comfortable angle.
• Bring the chair close to the desk for proper forearm support and backrest usage. Remove armrests if they hinder desk positioning.

Reference:

Getting your office space to work for you: How to select and use a chair

Working in the office — computer workstation checklist