Three calculators for the measurements people ask about most: how high the screen goes, how high the desk goes, and whether a chair fits you. Every number comes from OSHA’s Computer Workstations eTool, and every one is a range rather than a single figure.
Where to put the screen so you are not tipping your head back. This answers fit and comfort. It is not a treatment for neck pain, and no trial has shown that hitting these numbers prevents one.
How to measure this
Sit as you normally work, look straight ahead, and have someone measure from the floor to the outer corner of your eye. A mirror and a tape against a wall also works.
How to measure this
Measure from your eye to the front surface of the screen while sitting normally. OSHA gives a preferred range of 20 to 40 inches, which is 50 to 100 cm.
Top of the screen
Enter your measurements above
Why this number
OSHA: “The top of the monitor should be at or slightly below eye level.” So the top edge sits at your eye height or just under it.
Centre of the screen
Enter your measurements above
Why this number
OSHA: “The center of the computer monitor should normally be located 15 to 20 degrees below horizontal eye level.” The band is that angle worked through your own viewing distance, so it moves if you sit closer or further away.
Your viewing distance
Enter your measurements above
Why this number
OSHA: “Generally, the preferred viewing distance is between 20 and 40 inches (50 and 100 cm) from the eye to the front surface of the computer screen.”
If you miss the band, miss it low. OSHA notes that when a monitor is too high “you have to work with your head and neck tilted back”, and that holding that posture tires the muscles supporting the head. A screen slightly too low is the more forgiving error.
Source: OSHA Computer Workstations eTool, Monitors. Background: How High Should Your Monitor Be?
Work surface height for sitting and for standing. Both follow the same rule, because both are set by where your elbow lands.
How to measure this
Stand as you would at the desk, wearing the shoes you normally wear. Let your upper arms hang straight down and bend your elbows to a right angle. Measure from the floor to the underside of your elbow.
How to measure this
Same again but seated in your working chair, feet flat. Measure from the floor to the underside of the elbow.
Standing desk height
Enter your measurements above
Why this number
OSHA describes a neutral posture where the elbows “stay in close to the body and are bent between 90 and 120 degrees.” At 90 degrees the surface sits level with your elbow. Opening towards 120 degrees lowers it, which is where the bottom of the band comes from.
Seated desk height
Enter your measurements above
Why this number
The same elbow rule, measured seated. If your desk is fixed and too high, raising the chair and adding a footrest gets you to the same geometry.
What a standing desk has been shown to do. It reduces workplace sitting by about 100 minutes per workday in the short term, on evidence Cochrane graded low quality, falling to about 57 minutes at three to twelve months. That is a behaviour change. No health outcome has been demonstrated, and the same review found no clear effect on musculoskeletal symptoms.
Source: OSHA Computer Workstations eTool, Good Working Positions. Background: Do Standing Desks Actually Do Anything?
Whether a chair fits your body. Not whether it will protect your back: a 2022 review rated the evidence for chair interventions very low to low, and did not recommend them for back pain.
How to measure this
Sit with your feet flat and knees at a right angle, wearing your usual shoes. Measure from the floor to the crease at the back of your knee.
How to measure this
Sit right back in the chair. Measure horizontally from the back of your buttocks to the crease behind your knee.
Seat height
Enter your measurements above
Why this number
OSHA describes upright sitting as “the thighs are approximately horizontal, and the lower legs are vertical.” That puts the seat at about your popliteal height, so your feet rest flat without the seat edge lifting your thighs.
Seat depth
Enter your measurements above
Why this number
Shallower than your buttock to knee-back length, so the front edge does not press behind your knee while your back stays against the backrest.
What this does not tell you. Nothing here says a chair prevents back pain. Nobody has shown that. It is a fit check, and adjustability is the only chair property any standards body actually specifies.
Source: OSHA Computer Workstations eTool, Good Working Positions. Background: Does an Ergonomic Chair Help Back Pain?
Everything is worked out in your browser. No measurement you type is sent to us or to anyone else.
Read this before you trust the numbers
These are occupational health recommendations about comfort and fit. They are not findings from trials showing that hitting them prevents pain or injury. A Cochrane review of workstation adjustment found no effect on upper limb pain; a 2022 review rated the evidence for chair interventions very low to low and did not recommend them for back pain; standing desks change how long you sit but no health outcome has been demonstrated. OSHA itself says no single posture is the answer and that you should change position often.
If you have pain that radiates into an arm, numbness, tingling, weakness, or pain that followed an injury, that is a conversation with a clinician, not a desk adjustment. See the medical disclaimer.
Why we ask you to measure rather than just give your height
Most calculators of this kind ask for your height and work everything else out from it, using ratios that estimate where your elbow or knee sits as a fraction of your stature. Those ratios come from anthropometric surveys of particular populations, and they carry error for any individual standing in front of a desk. We would also be quoting numbers we cannot show you the source for.
Asking you to measure removes that step. A tape measure against a wall takes a minute, the result is yours rather than a population average, and every figure the tool then gives back is plain geometry applied to a published recommendation.
Common questions
Why is the answer a range instead of one number?
Because the sources give ranges. OSHA puts the centre of the screen 15 to 20 degrees below eye level and describes a neutral elbow as bent between 90 and 120 degrees. It also states that holding any one posture is not healthy and that you should move between positions during the day. A single number would be inventing a precision the guidance does not have.
Should I measure with shoes on?
Yes, wearing whatever you normally wear at your desk. Shoes change elbow and knee heights by a couple of centimetres, and the desk does not care what the tape says with bare feet.
My desk is a fixed height and it is wrong. What now?
Raise the chair until your elbows sit at the surface, then support your feet so your thighs stay roughly horizontal and your lower legs stay vertical. A footrest, or a stack of books, reaches the same geometry from the other direction.
Does any of this fix neck or back pain?
Nothing here has been shown to. The honest summary is that these are cheap, reversible adjustments with a comfort rationale and no demonstrated preventive effect. For neck pain specifically, the intervention with actual trial support is strength training, not furniture.
Do you sell any of this equipment?
No. There are no affiliate links on this page and no products are named. Every other calculator of this kind we are aware of is published by a company that sells desks or chairs.