What the Desk Ergonomics Checker does
This checker turns your measurements into working ranges for seat height, desk or keyboard height, screen height and viewing distance, then compares your current setup against them and says which parts sit outside the guidance.
It keeps two kinds of number strictly apart, and labels every row accordingly. The guidance figures - a viewing distance of 50 to 100 cm, the screen centre 15 to 20 degrees below eye level, elbows between 90 and 120 degrees, the keyboard at elbow height - are quoted from the OSHA Computer Workstations eTool, with the exact page recorded for each. The body-segment proportions used to estimate a measurement you have not taken are approximate population averages: they vary by several centimetres between people, so they always produce a range, and any measurement you supply replaces them outright.
How to use it
- Choose centimetres or inches and enter your height without shoes.
- If you can, measure yourself sitting upright with your feet flat: floor to the back of the knee, seat to elbow with the arm relaxed, and seat to eye. Each one removes a guess.
- Enter your current seat height, desk or keyboard height, screen top height, screen height and viewing distance.
- Read the ranges, then the comparison table: it says which of your settings are inside, just outside, or wrong by how much.
- Print or download the setup card and take it to the chair, rather than adjusting from memory.
Reading the results
Every recommendation says whether it came from a measurement, from published guidance, or from a proportion of your height. Estimated rows are ranges precisely because the proportion is approximate.
"Just outside" means within 2.5 cm of the range - close enough that the estimate itself could account for it. "Too high" or "too low" means the difference is larger than the uncertainty.
Screen angles are computed from your eye height, the screen top and the viewing distance. The guidance puts the top at or slightly below eye level and the centre 15 to 20 degrees below it; on a tall screen both cannot always be satisfied at once.
The comparison is geometry, not a diagnosis. Comfortable is a real datum, and a setup inside every range can still hurt if you do not move.
Worked example: a 175 cm person at a fixed 74 cm desk
With no measurements taken, the proportions give a popliteal height of 0.25 x 175 = 43.75 cm with a band of plus or minus 1.75, so a seat height range of 42.0 to 45.5 cm. The seated elbow rest is 0.145 x 175 = 25.4 cm, giving a keyboard height range of 65.6 to 72.6 cm around a midpoint of 69.1 cm.
The desk is a fixed 74 cm - about 1.4 cm above the top of that range, so it is reported as just outside rather than wrong. The advice is not to saw the desk: raise the chair to meet the keyboard, which puts the feet off the floor, and add a footrest. The page says exactly that, because with a fixed desk it is the only order that works.
Seated eye height comes out at 43.75 + 77.875 = 121.6 cm from the floor. A screen 33 cm tall whose top sits at 128 cm is therefore above eye level: the top edge is about 6.6 degrees above the eye line, so the head tilts back to read it. Lowering it so the top sits between 112.7 and 125.6 cm brings it into range.
At a 55 cm viewing distance the screen is inside the 50-100 cm guidance, though near its lower limit. As placed, its centre sits only 10.4 degrees below eye level - shallower than the 15 to 20 degrees OSHA suggests. Lowering the top to 120 cm puts the centre at 18.2 degrees, inside the band, with the bottom edge at 32 degrees and comfortably clear of the 60-degree maximum.
Formulas and scoring rules
- Seat height
popliteal height (floor to the back of the knee, feet flat)Estimated as 0.25 x standing height when not measured.- Keyboard height
seat height + seated elbow rest heightElbow rest estimated as 0.145 x standing height.- Seated eye height from the floor
seat height + seated eye heightSeated eye height estimated as 0.445 x standing height.- Screen top
between eye level and 5 cm below itOSHA: the top of the monitor should be at or slightly below eye level.- Downward angle to a point on the screen
atan((eye height - point height) / viewing distance)Guidance: 15-20 degrees to the centre, never more than 60 degrees to any part.- Sideways angle
atan(offset / viewing distance)Guidance: no more than 35 degrees off centre.
Which numbers are guidance and which are estimates
The guidance figures are quoted from the OSHA Computer Workstations eTool: at least 20 inches (50 cm) viewing distance and preferably 20 to 40 inches; the top of the monitor at or slightly below eye level with the centre 15 to 20 degrees below horizontal; a downward viewing angle never greater than 60 degrees; monitors no more than 35 degrees to either side; elbows close to the body and bent between 90 and 120 degrees; feet fully supported, thighs roughly parallel with the floor and knees about level with the hips. Those are public guidance, not a binding standard, and the data file names the page each came from.
The proportions are different in kind. Popliteal height at a quarter of stature, seated elbow rest at 0.145 and seated eye height at 0.445 are rounded population averages that differ by several centimetres between individuals and between populations. They exist so that someone who has not got a tape measure still gets a useful range - and every row that uses one says so.
The order of adjustment, and why the footrest keeps appearing
Set the chair to your body first: seat height so the feet are flat and the thighs roughly level. Then set the work surface to the chair, so the elbows are about level with the keyboard. Then set the screen to your eyes. Doing it in any other order means adjusting everything twice.
Most desks are fixed at somewhere between 72 and 76 cm, which is too high for a large share of adults. When the desk cannot move, the chair goes up to meet it and the feet no longer reach the floor - so a footrest is not an accessory, it is the second half of the adjustment. The alternative is a keyboard tray that brings the work surface down instead.
Geometry is the smaller half
The guidance that matters most is also the least numerical: change position often. No posture is healthy for hours, and the eTool says so directly - make small adjustments, stretch, stand up, take some tasks standing.
A perfectly measured workstation used motionless for eight hours is worse than an approximate one where the person moves. Treat the ranges here as a starting point that removes the obviously wrong settings, not as a target to hold still in.
Limitations: what the result does not prove
- It is not medical advice and cannot diagnose anything. Pain, numbness or tingling is a reason to see a clinician or your occupational health service, not to adjust a chair by two centimetres.
- Estimated measurements come from approximate population proportions. They differ by sex, age and population, and a tape measure beats them every time.
- It covers a seated single-screen workstation. Standing desks, dual monitors, laptops without an external keyboard, bifocals and wheelchairs all change the geometry in ways it does not model.
- The OSHA eTool is guidance, not a binding standard. Your jurisdiction, employer or display-screen-equipment assessment may require something different.
Privacy: where your data goes
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Standards and sources
- OSHA - Computer workstations eTool - checked 19 Sep 2026
- ISO 9241-5 - Workstation layout and postural requirements - checked 19 Sep 2026
- OSHA - Computer Workstations eTool: Good Working Positions
- OSHA - Computer Workstations eTool: Monitors
- OSHA - Computer Workstations eTool: Chairs
Frequently asked questions
What is the correct desk height for my height?
For a 175 cm person, roughly 66 to 73 cm to the keyboard surface, centred near 69 cm - but it follows from your seat height plus your seated elbow height, not from your stature directly. Measure those two and the range narrows considerably; the page shows which figures it estimated.
How high should my monitor be?
The top of the screen at or slightly below eye level, with the centre 15 to 20 degrees below horizontal eye level, and no part of it more than 60 degrees down. Enter your screen top, screen height and viewing distance and the page reports the actual angles.
How far away should a monitor be?
Between 50 and 100 cm (20 to 40 inches) from eye to screen, and at least 50 cm in any case. If you lean in to read, increase the text size rather than pulling the screen closer - leaning forward loses the backrest, which costs more than the eye strain saves.
My desk is too high and cannot be adjusted. What now?
Raise the chair until your elbows are about level with the keyboard, then put a footrest under your feet so your thighs stay roughly level and your feet are supported. A keyboard tray is the other option; resting the keyboard on books is not stable enough for daily use.
Do I need to measure myself, or is my height enough?
Height alone gives usable ranges, because the proportions used are population averages. Measuring your popliteal height, seated elbow height and seated eye height replaces those estimates with your own figures and narrows every range - and the page marks which rows are still estimated.
Should I use the armrests?
Only if they let your shoulders relax with your elbows close to your body, and only if they do not stop you getting close enough to the desk. Armrests that hold your arms up, or that collide with the desk edge, do more harm than having none.
Is a perfectly set up desk enough?
No. The guidance itself says that working in the same posture for prolonged periods is unhealthy however good the posture is. Change position frequently, stand up, and do some tasks standing - that matters more than the last centimetre of desk height.
Last reviewed by the A2Z.Tools team against the sources listed above.
