How to set up your office chair

Most office chairs have more levers than anyone ever touches. Learning how to set up your office chair is mostly a matter of working through them in a sensible order, because each adjustment changes the next. The guidance below comes from the UK Health and Safety Executive (HSE), the US Occupational Safety and Health Administration (OSHA) and Cornell University’s ergonomics programme. Much of it is practical convention rather than something tested in trials, and this page says so where it applies.

Why the order matters

The desk is usually the one thing you can’t change. So you fit the chair to the desk, your feet to the chair, and the screen to your eyes. HSE’s workstation checklist puts it in one line: adjust the chair height to get your arms in the right position, then adjust the screen height if necessary (HSE CK1).

If you’d like numbers for your height before you start, the desk and chair height calculator gives a starting point. Treat them as a first guess and fine-tune by feel.

How to set up your office chair, step by step

1. Seat height: start from the desk

Sit down and put your hands on the keyboard. HSE’s guidance is “keyboard just below elbow height”, with your shoulders relaxed: “try to position yourself high enough so you don’t need to shrug your shoulders” (HSE). A seat that is too low for the desk is what makes you shrug, and a shrug held for hours keeps the upper trapezius working.

OSHA describes the same target in more detail: elbows close to your body and bent between 90 and 120 degrees, forearms roughly parallel to the floor, and thighs roughly parallel too, with knees at about hip height (OSHA). NIOSH puts the hips and knees at, or slightly more than, a right angle (NIOSH).

There is some evidence behind the arm position. A study that followed 632 newly hired computer users found that typing with the elbows below the height of the keyboard’s home row was linked to a higher risk of neck and shoulder symptoms, and a slightly more open elbow angle (over 121 degrees) to a lower risk (Marcus et al., 2002). In plain terms: a keyboard that sits above your elbows is worth fixing.

Then check your legs. OSHA says the height is right when the whole sole of your foot rests on the floor, with the backs of your knees slightly higher than the seat (OSHA). HSE asks that the seat supports the front and back of the thighs equally (HSE). If the right height for the desk leaves your feet off the floor, don’t lower the chair. Use a footrest (step 6).

2. Seat depth: a small gap behind the knees

OSHA says the seat should support most of your thigh, without the front edge touching the back of your knee (OSHA). HSE gives a number: a gap of 2 to 3 cm between the front of the seat and the back of the knee (HSE). Pressure from the seat edge on the backs of the legs is something HSE specifically says to avoid (HSE INDG36).

Many chairs have a sliding seat for this. If yours doesn’t and the seat is too deep for you, a firm cushion behind your lower back brings you forward and gives back support at the same time. HSE suggests a cushion for extra back support anyway (HSE).

3. Backrest: use it, and let it recline a little

The picture of someone bolt upright at 90 degrees is not what the guidance asks for. Cornell’s guidelines say studies show the best seated posture is reclined at about 100 to 110 degrees, not the upright 90 degrees often shown (Cornell). OSHA wants a backrest that follows the curve of your spine, reclines at least 15 degrees from vertical, and either locks or has adjustable tension (OSHA).

What matters most is that you actually lean on it. HSE’s checklist asks whether the user has “a straight back, supported by the chair, with relaxed shoulders” (HSE CK1). In a survey of 634 frequent computer users, those who reported sitting with the trunk a little bent forward had almost three times the odds of low back pain compared with those who sat upright against the backrest (Snodgrass et al., 2024). It was a survey at one point in time, so it can’t show which came first, but it fits the advice. More on this in lower back pain from sitting.

4. Lumbar support: into the small of your back

OSHA describes it precisely: the outward curve of the backrest should fit into the small of the back, ideally with a height adjustment so it can sit where your lower back actually is (OSHA). That is the inward curve just above your belt, where the erector spinae run either side of the spine. If the chair has no lumbar support, OSHA suggests a rolled-up towel or a removable back cushion; HSE suggests a cushion (OSHA; HSE).

The research here is small. In a crossover study, 30 people with neck symptoms typed for an hour with and without a lumbar roll. With it, they held their head a little more upright for over half the session, but neck muscle load and neck discomfort barely changed (Takasaki et al., 2025). So a lumbar support may help you sit back more comfortably. It is not a treatment for forward head posture.

5. Armrests: support, not a perch

OSHA’s guidance is that armrests, if you have them, should be soft, let your shoulders relax and keep your elbows close to your body. If they can’t be adjusted properly or get in the way, remove them or stop using them (OSHA). HSE warns that chair arms can stop you getting close enough to the desk, which leaves you leaning forward to type (HSE CK1; HSE INDG36).

In the study of 632 computer users, having armrests on the chair was linked to a lower risk of neck and shoulder symptoms (Marcus et al., 2002). Cornell adds a caution: resting your forearms on the armrests the whole time you type or use the mouse is not a good idea (Cornell). A fair reading is to set them at or just below elbow height, use them when you pause, and lower them if they hit the desk edge. If your shoulders ache by the end of the day, see shoulder pain from computer work.

6. Feet: flat on something

HSE’s checklist asks whether your feet are flat on the floor without too much pressure from the seat on the backs of your legs, and if not, says a footrest may be needed (HSE CK1). It notes footrests are particularly useful for smaller users (HSE INDG36). OSHA says a footrest can be used when the desk height can’t be adjusted (OSHA). It doesn’t need to be special: NIOSH suggests a box or a book (NIOSH).

While you’re down there, clear the space. OSHA says the clearance for your legs under the desktop should generally be 50 to 72 cm high, and advises against storing things, such as a computer tower, where your legs should go (OSHA).

Once the chair is set, move on to the screen: how to set up your monitor.

What if your chair has hardly any adjustments?

HSE’s checklist lists what a work chair should have: stability, a seat that adjusts in height, a backrest that adjusts in height and tilt, and castors or glides (HSE CK1). If yours lacks some of these, you can still get close:

• Seat too low: sit on a firm cushion (HSE).
• Feet don’t reach: a box, a step or a stack of books.
• No lumbar support: a rolled towel at the small of your back (OSHA).
• Seat too deep: a cushion behind your back to bring you forward.
• Armrests in the way: take them off if you can.

If you work from a kitchen chair at home, the home office guide covers making a dining table work.

Is there a correct way to sit?

This is where the guidance and the evidence part company a little. An umbrella review of 41 systematic reviews found no consensus that particular spinal postures, or sitting itself, cause low back pain (Swain et al., 2020). Physiotherapy researchers have argued that the common belief that pain comes from sitting “incorrectly” lacks strong evidence (Slater et al., 2019). The UK’s Chartered Society of Physiotherapy says there is “no perfect posture or right or wrong desk set up”, and that “your best posture is your next posture” (CSP).

That doesn’t make the chair irrelevant. A review of five chair studies, three of them in garment factories, found that all five reported less pain straight after the chair change, though the authors rated the evidence as only moderate (van Niekerk et al., 2012). In one office trial, workers who got a highly adjustable chair plus training had less build-up of symptoms over the workday at 12 months. Training alone did not have that effect (Amick et al., 2003).

Taken together, the research points less to one correct posture than to a chair that fits you and the habit of changing position. OSHA suggests making small adjustments to your chair or backrest through the day, and standing up and walking around for a few minutes from time to time (OSHA). The microbreaks guide looks at how often, and the sitting time calculator shows how the hours of sedentary behaviour add up. And if you’re tempted by a strap-on fix instead, read do posture correctors work? first.

If your lower back or neck already aches by mid-afternoon, Bavelu’s sessions for the lower back, neck and shoulders are designed and filmed by physiotherapists, and are done at a desk, on a chair or on a mat, with no equipment.