Setting the Height, and Everything That Follows

Chair height is the first adjustment and the one that determines whether every other adjustment can work.

Start From the Floor

Sit with your feet flat on the floor and your knees at roughly a right angle.

Thighs should be level or sloping very slightly downward toward the knee. Sloping upward means the chair is too low, which rolls the pelvis backward and flattens the lower back.

There should be a gap of two or three fingers between the front edge of the seat and the back of your knees.

Then Check the Desk

• Elbows at roughly a right angle with forearms level
• Shoulders relaxed rather than raised
• Wrists straight rather than bent up over a keyboard
• If the desk is too high, raise the chair and add a footrest
• If it is too low, and it cannot be raised, that is the harder problem

Chairs with a usable height range, of the kind listed with their adjustment span at stellamia.org, matter because a fixed desk means the chair has to do all the accommodating.

The Footrest Is Not Optional

The step people skip, and it undoes everything else.

Most desks are a fixed height designed around an average, and anybody shorter than average has to raise the chair to reach the desk properly. That lifts their feet off the floor.

Dangling feet put the whole leg weight on the underside of the thighs, which compresses circulation and produces the numbness and pins and needles people blame on the seat.

A footrest, a box or a stack of books solves it entirely.

Do Not Chase the Screen

The common error. People raise or lower the chair until the screen looks right, which puts the arms and legs wrong.

Set the chair to your body, set the desk to the chair, then raise the screen to meet you. A monitor stand or a stack of books costs nothing.

Same Chair, Different People

A chair shared between people needs resetting each time, which nobody does.

For a home office used by two people at different heights, agreeing to adjust rather than tolerate is worth the ten seconds.

Check It Again in a Month

Chairs settle, gas cylinders lose a little travel, and people change shoes.

Shoes Change It

Heels change your effective leg length, and a setting that works barefoot does not in boots.

Write It Down

Once it is right, marking the cylinder saves resetting it after somebody else uses it.