BIFMA G1-2013, Ergonomics Guideline for Furniture Used In Office Work Spaces Designed For Computer Use ("BIFMA")
|Statements that don’t appear in BIFMA are in boxes like this. |
My advice: When purchasing a new chair, make note of where you are in the adjustment range of each setting. Ideally, you should not be at an endpoint in the range. For example, if your preferred seat height setting is the chair’s maximum height, you may be more comfortable with a chair that goes higher.
1. Seat Height
- Facilitates proper positioning of the upper body in relation to the height of the work surface.
- User is able to sit with their heels comfortably on the floor or footrest without undue pressure on the underside of the thighs.
- The torso-to-thigh angle should not be less than 90°
|My advice: Test your chair with the lowest and highest shoes that you wear. |
- Taller people sitting too low to accommodate a desk that is too low for them.
- Working at fixed height desks on chairs that are not high enough.
- Footrests that are too high or low for the required seat height.
- Click here for more advice on footrests
2. Seat Depth
- User is able to sit in the chair without undue pressure at the back of the knees, with adequate buttock and thigh support.
|My advice: A common recommendation is to have a 1-4 finger width gap between the front of the seat and your lower leg when you are sitting all the way back in the chair. |
3. Seat Width
- Wide enough to accommodate the full width of the buttocks
- See also Section 10 - Inside Distance Between Armrests (Pads/Caps)
|My advice: Select the narrowest seat that is wider than your buttocks. This will keep your armrests as close as possible. |
4. Backrest Height
- Maximum forward curve of the backrest should be at the height of the maximum inward curve of the lumbar spine [Research Finding: This point tends to be higher on those with high body mass indexes.]
- For users who prefer reclining postures, the height should provide support for the upper back and shoulders
|My advice: Head/neck support will reduce neck strain during reclined postures and if adjustable enough, can provide feedback on whether your head is moving forward.|
5. Backrest Width
- Wide enough to provide adequate support for the users back without causing localized pressure points
|My advice: Lateral curves (if any) should be appropriate for the width of the user and not force rounding of the shoulders. |
6. Lumbar Support
- Height and shape should support the lumbar spine. The support should not cause localized pressure points.
7. Movements of the Seat Pan and Backrest
- Should allow the user to sit in a position where the torso-to-thigh angle is equal to or greater than 90°
- The back support should stay in contact with the user’s back, especially in the lumbar area, as it reclines
- Should adjust to accommodate the varying postures assumed by the user throughout the day
|My advice: |
- Reclining may feel more comfortable but your desk may require you to sit more upright. Be sure to test your chair at the recline angles that you will be using while working.
- The ability to adjust the backrest angle independently of the seat angle can be useful to achieve a better fit.
8. Armrest Height
- Should allow the user to sit in a variety of postures while supporting their forearms and/or elbows in a manner that avoids lifting the shoulders (armrests too high) or leaning to the side/dropping the shoulders to reach the armrest (armrests too low)
9. Armrest Length and Position
- Should allow users to properly support their forearms while sitting close enough to the work surface to perform their tasks and maintaining contact with the backrest (i.e. armrests hitting the desk should not be limiting the user’s ability to sit close to their work)
- Should provide adequate support for the forearm without affecting wrist movement or causing excessive pressure on the elbow
|My advice: If you are unable to test the chair at a desk to assess whether or not the armrests will hit your desk, check that the armrest pads are not more forward than your wrists when your arms are in neutral. |
10. Inside Distance Between Armrests (Pads/Caps)
- Should support the forearms in a manner that avoids lifting the shoulders and/or forcing the elbows away from the body
- Inside distance between the armrests should allow the user to easily enter and exit the chair
|My advice: |
- Armrest pads should be wider than your forearm.
- Many armrests can be moved sideways, closer or farther away from the seat. Some have independently adjustable arm pads that can be brought closer than the width of the seat.
- Pads that can be repositioned by the user should not move unexpectedly if used for getting out of your chair.