Desk height calculator: what height should your desk be?

How to measure yourself

You need a tape measure, a firm flat chair and ideally a helper. Take your shoes off: the calculator adds them back separately.

1. Back of the knee. Sit with your thighs level, knees bent at a right angle and feet flat. Measure from the floor up to the crease behind your knee, where the calf meets the thigh. This sets the seat height.
2. Elbow above the seat. Let your upper arms hang by your sides and bend your elbows so your forearms point forward, level. Measure from the seat up to the underside of the elbow. This sets the desk or keyboard height.
3. Eyes above the seat. Sit tall and look straight ahead. Measure from the seat to the outer corner of your eye. This sets the top of the screen.

How the calculator works

Chair. The seat goes at the height of the back of your knee, plus your shoes. OSHA’s Computer Workstations eTool says the chair height is right when the whole sole of the foot rests on the floor, with the back of the knee slightly higher than the seat; the UK Health and Safety Executive (HSE) says the seat should support the front and back of the thighs equally. So treat the seat height as a maximum: a centimetre lower is fine, higher presses on the backs of your legs.

Desk. The keys go at elbow height: seat height plus your elbow height above the seat. OSHA says the elbows should be about the same height as the keyboard, with forearms roughly parallel to the floor; the HSE says just below elbow height. The desk goes lower by the height of your keyboard.

Screen. The top of the screen goes at eye level: seat height plus your eye height above the seat. The HSE’s checklist asks whether your eyes are at roughly the same height as the top of the screen, and Cornell University’s ergonomics guidance says to line your eyes up with the top of the viewing area. OSHA says at or slightly below eye level, with the centre of the screen 15 to 20 degrees below your eyes. The monitor distance calculator works out that window for your screen.

Estimating from your height. If you only know your height, the calculator multiplies it by body proportions from ANSUR II, a survey of 1,986 women and 4,082 men in the US Army measured between 2010 and 2012. For each measurement it takes the survey’s average divided by the average height, for women and for men, and uses the mean of the two: 0.242 of your height for the back of the knee, 0.141 for the elbow above the seat and 0.459 for the eyes above the seat. Standing, it uses 0.617 for the elbow and 0.934 for the eyes. Real people vary: across the survey, elbow height above the seat had a standard deviation of 2.6 cm in the women and 2.9 cm in the men, which is why your own measurement is better.

A worked example

Take the example above: 175 cm tall, in shoes with 2.5 cm soles, at a desk that adjusts. The back of the knee is about 175 × 0.242 = 42.3 cm, so the seat goes at 42.3 + 2.5 = 44.8 cm (17.6 in). The elbow sits about 175 × 0.141 = 24.7 cm above the seat, so the keys go at 69.5 cm; with a keyboard 2 cm tall, the desk goes at 67.5 cm (26.6 in). The eyes are about 80.3 cm above the seat, so the top of the screen goes at 125.0 cm from the floor, 57.6 cm (22.7 in) above the desk.

Now say the desk is fixed at 74 cm. That is 6.5 cm too high, so either raise the chair by 6.5 cm to 51.3 cm and put a 6.5 cm footrest under your feet, or fit a keyboard tray at 67.5 cm and keep the chair where it was. The screen rises with your eyes in the first case, so it still goes 57.6 cm above the desk.

If your desk doesn’t adjust

• Desk too high: raise the chair until your forearms are level with the keys, then support your feet. OSHA and the HSE both suggest a footrest when the feet no longer rest flat; a sturdy box works at home. OSHA also says a keyboard tray may be needed when the desk or chair can’t be adjusted.
• Desk too low: raise it on risers rather than hunch over it, and check there is still room for your thighs underneath.
• Chair too low and fixed, like most kitchen chairs: the HSE suggests a cushion to raise your seated position, and another behind your lower back if the backrest doesn’t support it.

Fitting a desk into a small room? Our sister site Tiny Room Life checks whether furniture fits the space.

Common mistakes

• Setting the desk first. The chair comes first because your feet and thighs fix the seat height; then the desk follows your elbows.
• Measuring barefoot, working in shoes (or the other way round). A 3 cm heel moves everything by 3 cm.
• Forgetting the keyboard. A desk at elbow height puts the keys a couple of centimetres too high.
• A screen that is too high, so you tip your head back. This is common with bifocals and progressive lenses; OSHA suggests lowering the screen for those.
• Armrests that stop you getting close. The HSE points out that chair arms can keep you too far from the desk; lower or remove them.
• Treating one posture as perfect. OSHA notes that sitting still in one posture for long periods is not healthy; the sit-stand planner and the 20-20-20 timer can remind you to move.