Seat Depth Adjustments on Your Office Chair

Office chair with arm rests.
Office chair with arm rests. Peter Anderson/Dorling Kindersley/Getty Images

How to Adjust Your Office Chair Seat Depth

Seat depth is a key chair adjustment to make if you want (or need) to work long hours at your computer without stressing your back. In the journey towards excellent office ergonomics, an optimal seat depth setting is second only to ideal seat height, in my opinion.

Problem is, many people (myself included) become confused when looking at the numerous knobs, buttons, bars and levers located in and around their chair.

Just because these controls are available for the tinkering doesn’t mean we know what to do with them. (Am I right?) If you are anything like me, identifying the lever for height is easy, but after that it’s all a blur.

Combine this with the fact that most of us feel we just don’t have the time to stop to figure out the hows and whys of adjusting our chairs. Suddenly it’s easy to understand why so many office workers complain about neck and back pain.

To remedy the confusion, let’s just take one chair feature--seat depth--and examine it carefully.  If you find yourself intrigued by office chair adjustments, you can continue reading about this topic in the other articles in this series:

Knobs and Bars and Levers, Oh My!

The gizmo that you’ll grab to adjust your chair’s seat depth may vary according to the design of the chair.

The three main types of seat depth adjustment designs are: The backrest slides, the seat slides or nothing slides.

If your chair is the type with the sliding back rest, it’s likely you’ll find a knob or lever at the back of the seat, right where the back rest attaches.

If your seat slides, then look left and try to locate a button or lever.

If it’s not there, the next place to look is under your seat in front. It will be a bar, like the one under your car seat. The last place the seat adjustment lever might be (if it’s not at left or in front) is on the right, in front. In this case it will probably be a small lever.

It’s also quite possible that you don’t have a seat depth adjustment all. (There is something you can do about this, so read on.)

The Ins and Outs of Forward and Back Seat Placement

When distilled down to its essence, the depth adjustment is just a forward-and-back placement of the seat pan. But chances are good this simple maneuver, however it's attained, will affect your pelvic position and, therefore, your spine and posture.

Ideally your pelvis and back will be in neutral, which can support you at sitting up nice and tall.

Related: How to Sit with Good Posture

Seat Depth Adjustment Time

For a chair that has a sliding back rest, just loosen the knob or push down on the lever to free it from the locked position. Then slide the back rest to the point where you can sit all the way back, with the seat coming to about mid-thigh level.

For a chair with a sliding seat, the tricky part is identifying the correct bell or whistle.

Use the information above in the "Knobs and Bars and Levers, Oh My!" section to guide you. Then push down on the apparatus (whatever type it is) and slide the seat to the desired position. Lock it into place. The way in which you lock it will depend on the design of the lever, paddle or gizmo you are using.

What If Your Chair Doesn’t Have a Seat Depth Adjustment?

If neither your chair seat nor your back rest can slide (sadly, the truth for most affordable office chairs), you might consider using a lumbar roll to help support your low back curve and maintain that forward position on the chair. Some office supply stores sell lumbar cushions with straps that affix to the chair.

You can also roll up a towel and use that; just make sure you arrange for some straps or other way to keep the roll connected to the chair's backrest.

Ideally, you’ll consider this important adjustment when purchasing your chair and find a model that does have an easy way to set the seat depth to fit your frame.


US Department of Labor. Computer Workstations. Chairs. Accessed August 25, 2011

Washington State Department of Labor and Industries website. Office Ergonomics: Computer Workstation & Mobile Computing.