The curved area of the chair should hit the small of your back in order to properly support your core. If it hits higher, see if the back of the chair is adjustable. If not, keep looking.
When seated, your knees should be even with your hips or lower (i.e. 90 degrees or more). To make that happen, choose a chair with an adjustable base.
Speaking of a base, you’ll want one that has five wheels as opposed to four (it will be more stable). Also, make sure the base is mounted to the center of the seat. If not, it can throw off your balance or even trip you as you stand up or sit down.
The depth of the seat is also a key factor. When sitting with your hips pushed as far back in the seat as they’ll go, you should be able to fit your fist between the back of your knees and the edge of the chair.
Is your office space hot? A mesh chair might be right for you. If you prefer a fabric or upholstered model, read the tags to be sure you aren’t allergic to any of the components.
Fixed arms can prevent you from pulling in close to your work station, making you strain. Look for a chair with adjustable arms that let you rest your elbows while you work (and take the tension out of your neck, shoulders, and back). Also, the arms should fit just under the desk so you can pull the chair up close and type comfortably.
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