What problem this solves
Most office setups use a 75 cm desk height because that’s the industry default. For an average adult (172 cm), it works. For a 160 cm user, the desk is too high — shoulders hike, wrists bend. For a 188 cm user, the desk is too low — the back rounds, the neck strains. The fix is to size the desk and chair to the person, using anthropometric ratios that account for leg length and torso length. This tool applies those ratios.
Monitor placement is the most-overlooked ergonomic detail. The eye should land at the top third of the screen, not the centre. Distance should be 50–70 cm for most screens (further for very large monitors, closer for laptops). Keyboard height should match seated elbow height, not the desk height. The calculator handles all four.
Who it’s for
- Home-office workers setting up a new desk
- Designers specifying workstations for multiple users
- HR managers buying ergonomic furniture for a team
- Therapists evaluating a client’s workstation setup
Why ratios, not just height
Anthropometric studies (the science of body measurement) give population averages: seated elbow height is 26% of standing height, eye level is 30%, etc. These ratios are surprisingly consistent across populations and ethnicities — a 172 cm Swedish adult and a 172 cm Japanese adult have nearly the same elbow height. The calculator uses these ratios as starting points.
Limitations
- Ratios assume average proportions; very long-legged or short-torsoed users may need adjustments.
- Heel height is an estimate — dress shoes vs. trainers differ by 5+ cm.
- Drawing/drafting desks need a tilted surface; not modelled.
- Sit-stand desks have different ergonomics — sitting position is the reference.
- Wheelchair users need a different seat reference point.
Practical rules of thumb
Sit with feet flat, knees at 90°. Forearms parallel to the floor when typing (elbows at 90–110°). The screen top should be 5–10 cm below seated eye level so you look slightly down at the centre. Document holders beside the screen, not flat on the desk (reduces neck rotation). Take a micro-break every 20 minutes — stand, stretch, look at something 6 m away.