Most lower back pain at a desk traces to one of five adjustable variables. Work through them in order: the fix is usually in the first three, and none of them require buying anything.
1. Seat height: knees at 90°, feet flat
If your seat is too high, your feet dangle and your thighs press into the seat edge, cutting circulation. Too low and your hips sink below your knees, rounding the lumbar curve. Most adults need a seat height between 42 and 53 cm. Adjust until your feet rest flat and your knees sit at roughly 90°.
2. Lumbar support: in the curve, not below it
The lumbar pad should press into the inward curve of your lower back, roughly belt height, not the flat area below it. A pad that sits too low pushes your pelvis forward and makes the pain worse. If your chair's lumbar height is fixed and lands in the wrong place, that's a chair problem, not a posture problem. Chairs with adjustable lumbar let you set both height and depth independently.
3. Seat depth: 2 to 3 fingers behind the knee
Sit fully back. If you can't fit two to three fingers between the seat edge and the back of your knee, the seat is too deep for your femur length: you'll slide forward to compensate and lose all back contact. This is the most common hidden cause of "my chair has lumbar support but my back still hurts." A seat-slide mechanism adjusts depth by ±50 mm in 10 mm steps.
4. Recline: use it, in the 100 to 110° band
Sitting bolt upright at 90° loads your lumbar discs more than reclining slightly. Research on seated disc pressure consistently favours a 100 to 110° torso-thigh angle for long sessions. Lock your recline there for focus work and open it up further for calls.
5. Movement: 2 minutes every hour
No chair eliminates the cost of stillness. Stand, walk, refill water: the best ergonomic chair is the one you regularly get out of.
When it is the chair
If the lumbar lands in the wrong place, the seat is too deep, or the recline doesn't lock, those are hardware limits. The Liberate's DynaFlex back keeps lumbar contact through the full recline range, which is the spec to look for if you shift posture often. For the full setup sequence including desk and monitor heights, see our workspace setup guide.