Desk Height Calculator

Elbow height is the whole calculation

Your desk is at the right height when your forearms lie level and your elbows sit between 90 and 120 degrees. That is the neutral posture OSHA's computer workstation guide describes, and it is the measurement everything else follows. A surface above that line pushes your shoulders up toward your ears. A surface below it drops your wrists into an upward bend that strains the tendons on the top of the forearm.

Height is the input because elbow height scales with stature. Standing elbow height lands close to 63 percent of a person's height, and seated elbow height close to 39 percent once the chair puts the thighs level. Two people who type the same hours can need work surfaces 6 inches apart, which is why one fixed desk height cannot fit an office.

The standard desk sold in the United States sits 28 to 30 inches above the floor, and 29 inches is the most common. Divide 29 by 0.39 and you get 74 inches, so a fixed desk at that height suits a person about 6 feet 2 inches tall. CDC measurements put the average American man at 68.9 inches and the average woman at 63.5, which means the typical desk runs 1 to 4 inches too high for the typical body.

Sources: OSHA's computer workstation desk guidance and CDC body measurement data.

The two ratios behind the numbers

Anthropometric tables list elbow height as a fraction of stature. The 50th percentile for standing elbow height lands near 0.63 of height, and seated elbow height lands near 0.39 with the thighs level. The calculator uses those two ratios, then subtracts 2 inches from the standing figure, because a typing surface should sit just below the elbow rather than at it.

The three formulas in one line each:

• Sitting: desk height = 0.39 x your height
• Standing: desk height = (0.63 x your height) minus 2 inches
• Chair: seat height = 0.25 x your height, plus your shoe heel

Sensitivity matters before you buy anything. Every inch of height moves the seated desk 0.39 inch and the standing desk 0.63 inch, so two users 4 inches apart differ by 1.6 inches seated but 2.5 inches standing. That is why tall and short people disagree far more about standing desks than about seated ones.

These are population medians, not a prescription for your arms. People with long torsos and short legs, or the reverse, sit outside the ratio, so treat the output as the starting position and then run the elbow test: sit or stand tall, let your arms hang, and see where your forearms land.

The posture rules and the keyboard ranges quoted above come from OSHA's workstation purchasing checklist (keyboard height 22 to 30 inches seated, 36 to 46.5 inches standing) and the Cornell University ergonomics guide.

Worked example: 5 feet 10 inches

Take a person 70 inches tall (178 cm) with a 0.5 inch shoe heel and no walking pad:

• Chair seat: 0.25 x 70 = 17.5, plus 0.5 for shoes = 18.0 inches
• Desk, sitting: 0.39 x 70 = 27.3 inches (69.3 cm)
• Desk, standing: 0.63 x 70 = 44.1, minus 2 = 42.1 inches (106.9 cm)
• Gap between the two: 42.1 minus 27.3 = 14.8 inches
• Top of the monitor, sitting: about 0.68 x 70 = 47.6, plus 0.5 = 48.1 inches
• Top of the monitor, standing: about 0.936 x 70 = 65.5, plus 0.5 = 66.0 inches

Now put the same person at the common 29 inch desk. The surface sits 1.7 inches above their 27.3 inch seated elbow line. Small as that sounds, it is enough to lift the shoulders, and it is the reason a keyboard tray that drops 2 inches fixes so many complaints. The 29 inch surface also falls 13.1 inches short of the 42.1 inch standing position, which is why a fixed desk and a stool is not a standing desk.

Add a 6 inch walking pad under the same person and the standing surface moves to 48.1 inches. Most standing desk frames top out between 48 and 50 inches, so the pad plus the shoe heel is what usually busts the range, not the desk.

Set the chair first, then the desk

The chair decides the desk height, so it goes first. Set the seat so your feet rest flat and your knees sit at or just below 90 degrees, which lands at about 0.25 of your height before shoes. If the seat is too high your feet dangle and your thighs press into the underside of the desk. If it is too low your knees ride up and your hips tilt backward.

A 5 foot 4 inch user illustrates the chain. Seat height is 0.25 x 64 = 16.0 inches, plus 0.5 for shoes = 16.5. The seated desk then works out to 0.39 x 64 = 25.0 inches, about 4 inches below the standard 29 inch surface. Since most task chairs bottom out near 16 inches, the fix is not a taller chair but a 4 inch footrest (or a keyboard tray that drops the work surface), and OSHA's desk guidance keeps 20 to 28 inches of clearance under the surface for legs and a footrest.

Armrests come next, set just below elbow height so the shoulders stay down while the forearms rest. Then the desk. Raise a seated user's chair to fit a 29 inch desk and the feet leave the floor by 3 to 4 inches, which is the classic sign the desk, not the person, is the problem.

Keyboard, mouse and monitor follow the desk

The desk surface sets the keyboard, not the other way around. On a desk matched to your elbow line, the keyboard sits on the surface with your wrists straight, and the mouse sits beside it at the same height so you never reach sideways. Cornell's ergonomics guide goes further and recommends a height adjustable tray with a slight negative tilt, which lets the keyboard sit below a writing-height surface while the wrists stay flat.

The monitor follows your eyes, not the desk. Put the top of the screen at or a touch below eye level, so your gaze falls about 15 to 20 degrees down to the middle of the display. For a 70 inch person seated, that top line sits near 47.6 inches, and for the same person standing it climbs to about 65.5 inches, a jump of nearly 18 inches, which is why monitors on standing desks need real height range and not a fixed riser.

Keep the screen 20 to 40 inches from your eyes, the distance OSHA gives as at least 20 inches at minimum. Laptops break every one of these rules at once, keyboard and screen welded together, so the fix is a riser for the screen and a separate keyboard and mouse at elbow height.

Screen distance and viewing angle follow OSHA's good working positions guidance.

Monitor height by body height

The desk sets the height for your hands; the monitor answers to your eyes. The usual rule is that the top of the screen sits at or just below eye level, and eye level runs about 0.68 of body height when seated and about 0.936 when standing, before adding the half inch of shoe. The calculator applies those same two ratios, and the table below shows where the top of the screen lands for common heights.

Read the seated column against the seated desk figures from the earlier table. A 5'8" user sits at a 26.5 inch desk with the screen top near 46.7 inches, which means the monitor must be raised on a stand or arm rather than sitting flat on the desk. Standing, the same user needs the screen top near 64.1 inches, so a monitor arm that reaches both positions is the practical fix for a mixed sitting and standing setup.

Fixed desks, standing desks and walking pads

Run the standing formula across adult heights and the band runs from about 36 inches at 5 feet 0 inches to 46 inches at 6 feet 4 inches, which matches OSHA's stated 36 to 46.5 inch range for standing keyboard surfaces. A desk that adjusts 38 to 46 inches covers most of the adult population, and anything narrower forces someone to shrug or slouch.

With a walking pad, add the deck height plus your shoe heel to the standing number. A 5 foot 10 inch user on a 6 inch pad lands at 42.1 plus 6 = 48.1 inches, and most frames stop near 50, so check the top of the range before buying either piece. Take an inch or two back off the desk when you walk, because the arms swing and the elbows sit a touch lower in motion.

Standing all day is not the goal either. Alternate in blocks, and treat the calculator output as the midpoint for each position. A soft mat underfoot at the standing position, and a footrest rail if you shift weight, does more for the long afternoon than another tenth of an inch of precision.

Mistakes that make a good desk feel wrong

The most common error is buying for the desk instead of the body. A 29 inch fixed desk is the store default, and it fits a 6'2" frame seated. Most people are shorter, so they raise the chair to reach the keyboard and then their feet dangle. A footrest solves the feet, but the cheaper fix is a keyboard tray that drops the work surface to the elbow line the calculator gives you.

The second error is setting a standing desk at full elbow height. The standing figure here already subtracts 2 inches, because typing happens just below the elbow with forearms level. If you raise the desk until your forearms tilt down or your shoulders creep up, drop it back down toward that minus 2 inch line and recheck.

The third error is forgetting the shoe. All seat heights on this page carry a 0.5 inch allowance for a typical sole. Anyone who works barefoot, or in heels, should add or remove that difference from the chair first; the desk only moves if the elbow line moves.