Fixed Desk Ergonomics Calculator
Measure your body, desk, keyboard, chair, and monitor to work out practical changes for a fixed-height workstation. The results give tape-measure starting points for the chair, footrest, keyboard, and screen rather than a generic height recommendation.
Recommended chair height (cm)52
- Natural chair height (cm)
- 45
- Footrest height (cm)
- 7
- Keyboard riser height (cm)
- 0
- Chair height-range shortfall (cm)
- 0
- Desk height mismatch (cm)
- 7
- Target monitor top height (cm)
- 127.92
- Monitor raise (+) or lower (-) (cm)
- 9.92
- Fixed-desk adjustment plan
- Raise the chair to 52 cm and add a 7 cm footrest. No keyboard riser is needed at the natural chair height. The recommended chair height is within the chair range. Raise the monitor by 9.92 cm.
All heights are in centimetres; a positive desk mismatch means the desk is high relative to the feet-supported starting position.
Measure seat height with the cushion compressed as it is while you work.
How to use this calculator
- Wear the shoes you normally use at the desk and measure floor-to-knee height with your feet flat.
- Measure elbow and eye height from the compressed seat surface while sitting in your usual working posture.
- Measure the fixed desk, the key surface above it, the chair maximum, and the visible screen position.
- Enter the measurements, then use the adjustment plan to check what your chair, footrest, keyboard support, and monitor stand can provide.
How the fixed-desk calculation works
The starting point is your floor-to-knee height, P. It is used as the natural chair height because it supports the feet on the floor when measured in normal work shoes. With seated elbow height E and keyboard height above the desk K, the feet-supported ideal desk surface is I = P + E - K. Desk mismatch is M = D - I, where D is the actual desk height. A positive mismatch means the desk is high; a negative value means it is low.
The chair height needed to bring the elbows level with the key surface is S = max(P, D + K - E). The footrest requirement is F = max(0, S - P), so raising the chair above its natural height calls for a footrest of the same height to keep the feet supported. When the desk is low at the natural chair setting, keyboard riser height is R = max(0, P + E - D - K). The chair-range shortfall is L = max(0, S - C), where C is the chair's maximum compressed seat height.
For the display, seated eye height from the floor is Y = S + Q, where Q is eye height above the seat. With viewing distance V, downward angle θ, and visible screen height H, target screen-center height is G = Y - V × tan(θ). The target top is T = G + H / 2. The calculator compares that with the current top U = D + B + H, where B is the screen bottom above the desk. The signed adjustment is A = T - U: positive means raise the monitor and negative means lower it.
What moves the result most
The elbow measurement, desk height, and keyboard thickness determine whether the setup needs a higher chair and footrest or a raised keyboard. A thick keyboard effectively makes a fixed desk higher. For the screen, eye height, viewing distance, and the selected angle matter most. Increasing the downward angle or moving the screen farther away lowers the target screen center.
Check the calculated movement against the actual adjustment range of the chair, monitor stand, and arm. If the chair cannot reach the calculated seat height, the shortfall signals that a different chair, a lower keyboard position, or other equipment change is needed. A monitor arm may also lack the travel needed for the indicated raise or lower.
What this calculator leaves out
This is a geometric starting point, not a clinical assessment. It assumes relaxed shoulders, elbows near a right angle, a conventional keyboard task, and accurate measurements from a compressed chair cushion. It does not account for armrest design, desk-edge pressure, input-device reach, screen glare, task-specific posture, visual prescriptions, mobility needs, or pain symptoms. Bifocal and progressive-lens users often need a lower and sometimes closer screen than the general target shown here.
Worked example
Suppose floor-to-knee height is 45 cm, seated elbow height is 25 cm, eye height above the seat is 75 cm, the desk is 74 cm high, and the key surface is 3 cm above the desk. The feet-supported ideal desk height is 45 + 25 - 3 = 67 cm, so the desk is 7 cm high. The chair height needed for the keys is 74 + 3 - 25 = 52 cm. That is 7 cm above the natural 45 cm chair height, so the starting plan is a 52 cm seat height with a 7 cm footrest.
With a 34 cm visible screen, a 60 cm viewing distance, a 15 degree downward angle, and the screen bottom 10 cm above the desk, target screen top height is about 127.92 cm. The current top is 74 + 10 + 34 = 118 cm, so the monitor should be raised about 9.92 cm. A 55 cm maximum chair has no shortfall in this example.
Common questions
What should I do when my fixed desk is too high?
If the desk and keyboard sit above your relaxed elbow height at the feet-supported chair setting, raise the chair until the key surface is near elbow level. Add a footrest equal to the chair increase so the feet stay supported. If the chair cannot rise far enough, the calculator shows the height shortfall to solve with equipment that has more range.
Should I raise my chair or use a keyboard tray?
For a high fixed desk, the calculation first raises the chair and adds a footrest if needed. A lower keyboard tray can be useful when the chair range is insufficient or the raised chair makes the rest of the desk unsuitable. For a low desk, the calculated keyboard riser shows the opposite problem: the key surface needs to come up rather than the chair going below the feet-supported height.
How high should a footrest be under a desk?
In this calculation, footrest height equals the amount the recommended chair height exceeds your natural floor-to-knee height. That preserves support under the feet after the chair is raised for a high desk. Check that the footrest is stable and large enough to use comfortably through the range of postures you adopt.
Where should the center and top of my monitor be?
The calculator places the screen center below your eye height by the vertical drop created by your selected viewing distance and downward angle. It then adds half the visible screen height to find the target top. This is a starting geometry, not a rule that overrides a comfortable viewing position or an eye-care professional’s advice.
Why are measured body dimensions better than height alone?
Overall stature does not reliably tell you seated elbow height, knee height, torso length, or eye height. Those proportions directly determine the relationship between the chair, key surface, and screen. Measuring them also includes the effect of normal work shoes, which can change the feet-supported seat height.
What changes are appropriate for bifocal or progressive-lens users?
Bifocal and progressive lenses may lead you to tilt your head back to see a high screen through the appropriate lens area. A lower and sometimes closer monitor can reduce that tendency, depending on the prescription and task. Use the result as a starting point and discuss persistent visual or neck symptoms with an appropriate professional.