What is the optimal height (from floor) of a computer keyboard?

Hi cathynap,

Generally, optimal placement of keyboards should be determined by both
the size and task of the user.

"Overall Concept: Placement of Computer Input Devices 
Optimally, the user should be able to use the keyboard and mouse or
other inputdevices with his/her arms close to the torso. In other
words, upper arms should not have to extend very far forward to reach
the keyboard or the mouse. In addition, the forearms should be
approximately parallel to the floor when keying. There should be no
more than a very slight reach up or down."

ErgoDynamix: Keyboard Placement
http://www.ergodmx.com/articles/article_7.html


The following are excerpts of articles and documents regarding the
optimal height of the keyboard to the floor. I suggest you read the
articles in their entirety for a clearer overall understanding.

Keyboard height- 
"This element has a large impact on comfort and freedom of the
shoulders and arms. Each person has a different length of trunk and if
the distance of the keyboard to the floor is too high it results in an
increase in physical discomfort to the neck-shoulder-arm-hand region.
This is because the shoulders become chronically elevated and the
upper arms are also compensating with sideward elevation. The muscles
of the neck and upper shoulder, particularly the trapezius and
deltoids, are overstrained.

Optimal distance of keyboard to floor ranges between 73-85 cm. If the
workstation is not adjustable then it is essential that the chair
position support this ideal range. If the chair seat is adjusted,
adjustments to the feet are necessary. Use a slant board or even
telephone books for your feet so that they do not dangle."

University of British Columbia - School of Library, Archival and
Information Studies: The Workstation
http://www.slais.ubc.ca/courses/libr500/01-02-wt2/www/L_Smith/workstation.htm#Hand%20to%20keyboard%20distance


"Measurement A: Sitting Elbow 
Adjust the chair so your feet are firmly on the floor and your knees
are even to or slightly lower than your hips.
Relax your shoulders, place your hands in your lap, then raise your
hand even with your elbow.
Ask your ergo buddy to measure the distance from the floor to your elbow. 

Measurement B: Keyboard/Mouse Surface
There are three options for the height of the surface that supports
the keyboard and mouse depending on what type of keyboard you use and
on your typing style. In any case, the keyboard and mouse should never
be higher than your elbows. Using the Sitting Elbow height you
measured above (Measurement A), determine the correct keyboard/mouse
surface height for yourself as follows:
1" lower than Measurement A for an ordinary keyboard. 
2" lower than Measurement A if the MS Natural keyboard is used 
Equal to Measurement A if you look at your hands to type."

Working Well - Workstation Design
What is the Optimal Keyboard, Mouse and Monitor Height?
http://www.working-well.org/wkstn_design.html 


"Proper keyboard height helps keep the wrists from bending while
typing. This improves the comfort of the hands, wrists, and forearms.
The preferred working position is as follows:

Set hands with the fingers on the middle row of the keyboard. Arms
should be parallel to the floor and the elbows at the sides. Wrist
should be in line with the forearm. The neutral posture for wrists is
a straight (handshake) position.

If the wrists are not straight, adjust the keyboard. Look for forearms
to be parallel to the floor and wrists straight while keying. If the
keyboard height is not adjustable, adjust your chair height. Make sure
your feet remain flat on the floor or you will need a footrest..."

Caltech Safety Office: Ergonomics in Office Environments
http://www.safety.caltech.edu/ergonomics/office.html 


"...Now, while still sitting in the chair and without reference to any
table, arrange hands and arms in the most comfortable typing or
writing position. Keep your wrists straight. With a steel tape or
yardstick, measure the distance from the floor to your fingertips.
Subtract thickness of your keyboard from that height and jot it down.
Now measure the distance from the floor to the bottom of your elbow.
If there is a great difference, you may be angling your arms (or
usually your wrists) up or down too much. Alter your arm angle to
match the elbow height and see if this isn't better.

Theoretically, the top of your keyboard should be the same height
above the floor as the bottom of your elbows. This distance (minus the
thickness of the keyboard) is the optimal height for your typing-table
top..."

LookSmart - Find Articles: A home-built office desk-Do It Yourself
http://www.findarticles.com/p/articles/mi_m1279/is_n153/ai_17907755 


Some more very interesting sites:
Ergonomics: How to sit at a computer
http://www.ergonomics.com.au/howtosit.htm

Precision: Workstation Layout
http://www.precision.com/Ergonomics/Ergonomic_Workstation_Layout.htm

Ergo In Demand: Ergonomic Design for your Computer Workstations
http://www.ergoindemand.com/computer-workstation-ergonomics.htm


Search criteria:
optimal distance floor keyboard
optimal height floor keyboard


I hope this is helpful. If you have any questions regarding my answer
please don't hesitate to ask before rating it.

Best wishes,
Rainbow