In the USA, the Occupational Safety and Health Administration (OSHA) is offering a purchasing guide checklist that can help you find the proper equipment you need.
They also offer a checklist on good working positions that I reproduced below.
The workstation is designed or arranged for doing computer tasks so it allows your:
- Head and neck to be upright, or in-line with the torso (not bent down/back). If "no" refer to Monitors, Chairs and Work Surfaces.
- Head, neck, and trunk to face forward (not twisted). If "no" refer to Monitors or Chairs.
- Trunk to be perpendicular to floor (may lean back into backrest but not forward). If "no" refer to Chairs or Monitors.
- Shoulders and upper arms to be in-line with the torso, generally about perpendicular to the floor and relaxed (not elevated or stretched forward). If "no" refer to Chairs.
- Upper arms and elbows to be close to the body (not extended outward). If "no" refer to Chairs, Work Surfaces, Keyboards, and Pointers.
- Forearms, wrists, and hands to be straight and in-line (forearm at about 90 degrees to the upper arm). If "no" refer to Chairs, Keyboards, Pointers.
- Wrists and hands to be straight (not bent up/down or sideways toward the little finger). If "no" refer to Keyboards, or Pointers
- Thighs to be parallel to the floor and the lower legs to be perpendicular to floor (thighs may be slightly elevated above knees). If "no" refer to Chairs or Work Surfaces.
- Feet rest flat on the floor or are supported by a stable footrest. If "no" refer to Chairs, Work Surfaces.
Consider these points when evaluating the chair:
- Backrest provides support for your lower back (lumbar area).
- Seat width and depth accommodate the specific user (seat pan not too big/small).
- Seat front does not press against the back of your knees and lower legs (seat pan not too long).
- Seat has cushioning and is rounded with a "waterfall" front (no sharp edge).
- Armrests, if used, support both forearms while you perform computer tasks and they do not interfere with movement.
"No" answers to any of these questions should prompt a review of Chairs.
Consider these points when evaluating the keyboard or pointing device. The keyboard/input device is designed or arranged for doing computer tasks so the:
- Keyboard/input device platform(s) is stable and large enough to hold a keyboard and an input device.
- Input device (mouse or trackball) is located right next to your keyboard so it can be operated without reaching.
- Input device is easy to activate and the shape/size fits your hand (not too big/small).
- Wrists and hands do not rest on sharp or hard edges.
"No" answers to any of these questions should prompt a review of Keyboards, Pointers, or Wrist Rests.
Consider these points when evaluating the monitor. The monitor is designed or arranged for computer tasks so the:
- Top of the screen is at or below eye level so you can read it without bending your head or neck down/back.
- User with bifocals/trifocals can read the screen without bending the head or neck backward.
- Monitor distance allows you to read the screen without leaning your head, neck or trunk forward/backward.
- Monitor position is directly in front of you so you don't have to twist your head or neck.
- Glare (for example, from windows, lights) is not reflected on your screen which can cause you to assume an awkward posture to clearly see information on your screen.
"No" answers to any of these questions should prompt a review of Monitors or Lighting/Glare.
Consider these points when evaluating the desk and workstation. The work area is designed or arranged for doing computer tasks so the:
- Thighs have sufficient clearance space between the top of the thighs and your computer table/keyboard platform (thighs are not trapped).
- Legs and feet have sufficient clearance space under the work surface so you are able to get close enough to the keyboard/input device.
Check to see if the:
- Document holder, if provided, is stable and large enough to hold documents.
- Document holder, if provided, is placed at about the same height and distance as the monitor screen so there is little head movement, or need to re-focus, when you look from the document to the screen.
- Wrist/palm rest, if provided, is padded and free of sharp or square edges that push on your wrists.
- Wrist/palm rest, if provided, allows you to keep your forearms, wrists, and hands straight and in-line when using the keyboard/input device.
- Telephone can be used with your head upright (not bent) and your shoulders relaxed (not elevated) if you do computer tasks at the same time.
"No" answers to any of these questions should prompt a review of Work Surfaces, Document Holders, Wrist Rests or Telephones.
- Workstation and equipment have sufficient adjustability so you are in a safe working posture and can make occasional changes in posture while performing computer tasks.
- Computer workstation, components and accessories are maintained in serviceable condition and function properly.
- Computer tasks are organized in a way that allows you to vary tasks with other work activities, or to take micro-breaks or recovery pauses while at the computer workstation.
Finally, when it comes to shopping for a good chair, you may want to look at this article from Wirecutter.