You've invested in a quality ergonomic chair, but are you actually using it correctly? Studies suggest that up to 70% of office workers don't properly adjust their chairs, essentially negating the ergonomic benefits they paid for. Even the most expensive Herman Miller or Steelcase chair will cause discomfort if it's not configured for your specific body and workspace. This guide walks you through every adjustment, step by step, to ensure you're getting maximum support and comfort from your seating.
Before You Begin: The Foundation
Chair adjustment doesn't happen in isolation—it's part of a larger ergonomic setup that includes your desk, monitor, keyboard, and mouse. Before adjusting your chair, ensure your desk is at a standard height (typically 73-76cm for fixed desks) and your monitor is positioned at arm's length away. Your chair adjustments will be based on achieving optimal positioning relative to these elements.
Wear the shoes you typically wear while working, as even a few centimetres of heel height affects the correct seat height. If you work barefoot at home, adjust accordingly. Have a measuring tape handy—we'll reference specific measurements to verify your positioning.
The goal of chair adjustment is to maintain your spine's natural S-curve while keeping all major joints (ankles, knees, hips, elbows) at approximately 90-degree angles. Every adjustment works toward this goal.
Step 1: Adjust Seat Height
This is the foundation of all other adjustments. Start by standing in front of your chair and adjusting the height so the highest point of the seat pan is just below your kneecap. Then sit down and check the following:
- Your feet should rest flat on the floor (no tippy-toes, no dangling)
- Your thighs should be parallel to the floor or angled very slightly downward
- There should be a small gap (about 2-4 fingers' width) between the back of your knees and the front edge of the seat
- Your knees should be bent at approximately 90-100 degrees
If you can't achieve flat feet on the floor while maintaining proper thigh positioning, you may need a footrest. This is common for shorter individuals or when desk height can't be adjusted. The footrest should position your feet at the same angle as if they were on the floor.
Many people sit too high, causing their feet to dangle or rest only on their toes. This compresses blood vessels behind the thighs and leads to circulation problems, numbness, and increased fatigue.
Step 2: Set Seat Depth (If Adjustable)
Seat depth adjustment, sometimes called seat pan slide, controls how far forward or back the actual seat extends. Not all chairs have this feature, but if yours does, it's crucial for proper thigh support.
Sit all the way back in your chair so your lower back contacts the lumbar support. Now check the space between your calves and the front edge of the seat. You should have approximately 5-8cm (about three finger-widths) of clearance. This ensures:
- Your thighs are supported along most of their length
- No pressure on the back of your knees (which would restrict circulation)
- You can still engage the lumbar support without sliding forward
If your chair doesn't have seat depth adjustment and the seat is too deep for your leg length, consider using a lumbar support cushion to effectively bring the backrest forward toward you.
Step 3: Configure Lumbar Support
Proper lumbar support is perhaps the single most important element of ergonomic seating. Your lower spine naturally curves inward (lordosis), and maintaining this curve while seated prevents the disc compression and muscle fatigue that cause lower back pain.
Height Adjustment
If your chair has height-adjustable lumbar support, position it so the most prominent part of the support sits in the curve of your lower back. For most people, this is roughly at belt level or just above—typically between the L3 and L5 vertebrae. You should feel gentle, even pressure across your lower back, not a point pressing into your spine.
Depth Adjustment
If available, depth adjustment controls how much the lumbar support protrudes. Start with minimal depth and gradually increase until you feel supported but not pushed forward. The support should fill your lumbar curve without forcing you into an unnatural arch. If you feel like you're being pushed away from the backrest, reduce the depth.
It takes your muscles time to adapt to proper lumbar support, especially if you've been sitting with poor posture for years. Start with less aggressive support and gradually increase depth over several weeks as your body adjusts.
Step 4: Adjust the Backrest Recline
Contrary to popular belief, sitting bolt upright at 90 degrees isn't optimal. Research suggests a slight recline of 100-110 degrees reduces spinal disc pressure while maintaining good support. Most ergonomic chairs offer both recline angle adjustment and tension control.
Recline Angle
For focused desk work, set your recline to approximately 100-105 degrees—just slightly leaned back. For reading or thinking tasks, a more reclined position (110-120 degrees) can be comfortable. Avoid extreme reclines during active work, as this forces you to crane your neck forward to see your screen.
Tension Control
The tension knob (usually under the seat) controls how much resistance the chair provides as you recline. Adjust this based on your body weight and preference. The chair should support you without collapsing backward, but allow you to lean back without excessive effort. As a starting point, you should be able to recline using just your body weight without needing to push.
Step 5: Position Armrests
Armrests reduce strain on your shoulders, neck, and upper back by supporting the weight of your arms. Improperly adjusted armrests, however, can cause just as many problems as they solve.
Height
Adjust armrest height so your elbows rest at approximately 90 degrees when your shoulders are relaxed (not shrugged up or reaching down). Your forearms should be roughly parallel to the floor when resting on the armrests. At this height, you should feel your shoulder muscles release tension.
Width
If your armrests adjust laterally, position them so your elbows rest comfortably without splaying your arms outward or squeezing them against your body. There should be just enough room to sit naturally.
Depth and Angle
Advanced armrests (4D) allow forward/backward and angle adjustments. Position them so you can rest your forearms while typing without reaching forward or pulling your arms back. A slight inward angle often feels natural for keyboard work.
If your armrests prevent you from pulling close enough to your desk, consider lowering them during intensive typing sessions. Some users prefer removing armrests entirely if they frequently hit desk edges—though this should be a last resort.
Step 6: Adjust the Headrest (If Equipped)
Not all chairs have headrests, and not everyone needs one for standard office work. However, if your chair includes a headrest and you experience neck strain, proper adjustment can help.
The headrest should support the natural curve of your neck, with the cushion resting against your head (not pushing it forward). It's primarily useful for:
- Reclining during thinking or reading tasks
- Video calls where you're looking at the camera for extended periods
- People with existing neck issues who benefit from additional support
For most focused desk work, you may not actively use the headrest. That's normal—it's there when you need occasional neck support, not for constant contact.
Fine-Tuning and Verification
After completing all adjustments, spend at least 30 minutes working in your newly configured chair. Pay attention to any discomfort or strain. Minor tweaks are normal as you dial in the perfect setup.
Every few weeks, revisit your adjustments. Bodies change, clothing changes with seasons, and it's easy to unconsciously mis-adjust something over time. A quick monthly check keeps your setup optimised.
Remember that even perfect chair adjustment doesn't replace the need for movement. Regular stretching and standing breaks remain essential for long-term health. Your chair supports you while seated—but the best thing you can do for your body is to not sit constantly.