The word appears on almost every office chair sold, including ones with no adjustment at all, so it is worth knowing what it should describe.
It Means Adjustable to a Person
Ergonomics is the practice of fitting equipment to the human using it, rather than expecting the human to adapt.
A chair cannot be ergonomic in the abstract, because bodies differ enormously in leg length, torso length, hip width and weight. What makes a chair ergonomic is that it can be adjusted to fit a specific person.
A fixed chair with a curved back is a shaped chair. It is not an ergonomic one.
The Adjustments That Matter
- Seat height, which sets everything else
- Seat depth, so the seat front does not press behind the knees
- Backrest height or lumbar position, to meet your actual lower back
- Armrest height, and ideally width and angle
- Recline, with tension you can set to your weight
Ranges that list which adjustments each model has, of the kind at stellamia.org where lumbar support and recline range are stated per chair, allow the comparison. A listing that only says ergonomic does not.
Height Is the One That Matters Most
If nothing else adjusts, this should. Everything else follows from it.
Feet flat on the floor, knees at roughly a right angle, thighs level or sloping very slightly downward. From there the desk height determines whether your elbows sit right.
Almost every discomfort complaint traces back to a chair set at the wrong height and everything compensating for it.
The Chair Is Half the Problem
Worth being honest about. A superb chair at the wrong desk height, or in front of a screen that is too low, does not solve anything.
The chair, the desk and the screen are one system. Adjusting one without the others moves the problem rather than fixing it.
Movement Beats Posture
The finding that matters most and is least sold.
No single position is good for hours, including a perfect one. Getting up regularly, changing position and taking short breaks does more than any equipment.
A chair that makes it easy to shift and recline is doing something a rigid one cannot.
Certification Means Testing
Standards such as BIFMA cover strength, stability and durability testing. They are about the chair not failing rather than about comfort.
Try Before Committing
Fit is personal, and a return window matters more here than a specification.
Adjust It on Day One
Most people never touch the levers.