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 an excellent office ergonomic set up, an optimal seat depth setting is second only to ideal seat height.

The problem is, many people become confused when presented with the numerous knobs, buttons, bars and levers located in and around their chair.

While such controls are readily available for the tinkering, and make for good marketing conversations, this doesn't guarantee we will know what to do with them once the chair is safely in our office.

In other words, identifying the lever for height is easy for most office workers, but after that, it’s all a blur.

Combine this with the time factor. Figuring out the hows and whys of adjusting a chair will likely mean you have to block off at least fifteen minutes in your calendar. Suddenly, it becomes easy to understand why so many office workers complain about neck and back pain.

To remedy the confusion, let’s just take one chair features — the 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 brand and design of the chair. That said, there are three main types of seat depth adjustment designs: 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, 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. In this case, 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, which is covered later in this article.

How Seat Depth Adjustment Relates to Your Posture

In essence, the depth adjustment is the forward-and-back placement of the seat pan. Regardless of the way it's attained, seat pan depth will likely affect your pelvic position and, therefore, your low back posture. The overall goal is a neutral, upright pelvic position, which in turn, may help support your posture and avoid back pain.

How to Adjust Seat Depth

If your chair has a sliding back rest, adjust the seat depth by loosening the knob or pushing 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  edge 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.

If Your Chair Doesn’t Have Seat Depth Adjustment Controls

If neither your chair seat nor your back rest can slide, which is the case with most of the less expensive office chairs, you might consider using a lumbar roll.

A lumbar roll may help support your low back curve as well as help you 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, though, 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.

Sources:

US Department of Labor. Computer Workstations. Chairs. http://www.osha.gov/SLTC/etools/computerworkstations/components_chair.html. Accessed August 25, 2011

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