Ergonomic Desk Calculator

Ergonomic Desk Calculator for sitting, standing and sit-stand desks. Enter your barefoot height and screen size to get the chair seat, desk and monitor heights that suit your body.

Fitting a Desk With the Ergonomic Desk Calculator

The Ergonomic Desk Calculator takes your barefoot height and works out a chair seat, a desktop height and a screen position that fit your body. It also checks whether your current desk and chair can be made to work before you build or buy anything.

It suits woodworkers building a desk from scratch, anyone choosing a sit-stand frame, and people trying to fix a desk they already own. Results come in inches or centimeters, measured from the floor.

Scaling Your Height With ANSUR II Proportions

Height alone does not tell you where your elbows or eyes are. The calculator scales your height by body ratios from ANSUR II, the 2012 US Army anthropometric survey of 4,082 men and 1,986 women.

Each body measurement is divided by that group's average stature, so popliteal height, sitting elbow height and eye height become fractions of your height. You can use the men's ratios, the women's ratios or the average of the two, which is the default.

The survey measured soldiers, so the ratios describe an average body. Someone with long legs for their height will want a slightly higher seat than the ratio gives, which is why the results are a starting point to fine-tune by feel.

Seat First, Then the Desktop

The chair seat sits at popliteal height, the floor-to-back-of-knee measurement, plus your shoes. That lets your feet rest flat with the thighs level.

$$S=r_p\cdot H+s$$

The desktop then sits at seated elbow height minus the height of your keyboard's home row, so your forearms stay level while typing.

$$T=S+r_e\cdot H-k$$

For a 70 in person with average proportions and 1 in of shoe, the seat lands at 17.9 in and the elbows at 27.8 in. Taking off a 1.2 in keyboard puts the desktop at 26.6 in, about 26-5/8 in on a tape.

Keyboard height matters more than it looks. ANSI/HFES 100-2007 prefers a home row 30 mm (1.18 in) or less above the desk and says it should not exceed 35 mm, and every extra 1/4 in of keyboard drops the ideal desktop by the same 1/4 in.

The same seat height also fixes how much room your thighs have. The calculator subtracts the desktop thickness and your seated thigh height, and at 70 in with a 1 in top only about 1/2 in is left, so a desk with a deep apron would hit your legs. The Table Leg Calculator handles knee clearance under the apron when you build the frame.

Where the Screen Should Land

The OSHA Computer Workstations eTool sets the screen 20 to 40 in from the eyes, with its center 15 to 20 degrees below horizontal eye level. The top of the screen should be at or slightly below eye level.

The calculator drops the screen center from your eye height along that gaze angle, then works out the screen height from its diagonal and shape.

$$C=E-d\cdot \sin (\theta )$$

$$h=\frac{D_{diag}}{\sqrt{r^2+1}}$$

Here d is the eye-to-screen distance, theta is the gaze angle and r is the aspect ratio, 16/9 for a standard widescreen. A 24 in 16:9 screen is 11-3/4 in tall, and at 24 in away and 15 degrees its top sits 3/8 in below the eyes of a 70 in person.

Screen size changes the answer. At the same distance and angle a 27 in screen's top rises 3/8 in above eye level and a 32 in screen rises 1-5/8 in above, so bigger screens need more distance or a steeper gaze to stay within OSHA's guidance.

Two screens side by side are the other trap. OSHA keeps screens within 35 degrees left or right, but two flat 24 in screens at 24 in put the outer edges about 42 degrees off center, so move them back to roughly 31 in or angle the side screens inward.

Making an Existing Desk Work

An existing desk is often the fixed point you have to work around. If your desk is 29 in and the ideal is 26.6 in, raise the chair 2.4 in to bring your elbows up to the keyboard, then add a footrest of the same 2.4 in so your feet stay supported.

That fix only works if the chair can reach the new seat height. ANSI/HFES 100-2007 asks adjustable chairs to cover at least 4.5 in of travel within 15 to 22 in, and if yours tops out too low the results suggest a keyboard tray set below the desk instead.

A desk that is too low gets risers under each leg. For standing work at a fixed desk, the results give the height of desktop converter that closes the gap to your standing elbow height.

Sit-Stand Frames and the HFES Range

The ANSI/HFES 100-2007 work surface checklist asks sit-stand surfaces to adjust between 56 and 118 cm (22 and 46.5 in). The Sit-Stand Desk option checks both of your heights against that range.

HFES itself notes that the 2007 standard is no longer maintained as an American National Standard, with a redevelopment started in 2025. Its 22 to 46.5 in range remains a useful check, so compare your frame's listed travel against both of your numbers.

The calculator accepts heights from 48 to 90 in, gaze angles from 0 to 45 degrees and one to four monitors. Entries outside those limits, or a chair range whose highest seat is not above its lowest, stop the results until they are fixed.

Desk Height Questions

What desk height fits my height?

With average proportions, 1 in shoes and a 1.2 in keyboard, a 5 ft 4 in person needs a sitting desk near 24-3/8 in and a standing desk near 39-1/4 in. At 6 ft 0 in those become about 27-3/8 in and 44-1/4 in.

The heights table in the results lists every 2 in step from 5 ft to 6 ft 4 in. Each row uses your own shoe, keyboard and proportion settings, so the numbers shift when you change them.

Should the desktop be at elbow height?

The keyboard's home row should be at elbow height, not the desktop itself. That is why the calculator subtracts the keyboard height from your elbow height before giving a desktop figure.

For a writing desk or drafting table with no keyboard, set the keyboard height to 0. The desktop then lands right at elbow height, which suits handwriting and hand tools.

Do I measure my height with shoes on?

Measure barefoot against a wall, then set the footwear allowance for what you actually wear at the desk. The allowance raises your seat, elbows and eyes by the same amount.

The default is 1 in, and the presets run from barefoot up to 1-1/2 in. Working in socks means setting it to 0, which lowers the seat, desk and screen by a full inch.

How much lift does a standing desk need?

The lift is the gap between your sitting and standing desktop heights. For a 70 in person with the default settings that is 26.6 in to 43.0 in, a travel of about 16.4 in.

Taller users need both a higher top position and more travel. Check that the frame goes low enough as well. HFES set the 56 cm (22 in) bottom of its range so a seated 5th percentile woman is accommodated.