Setting aside the fact that kids come in different sizes, the desks that the schools get that they can adjust can be set for a to-top height of something over 20 inches to something under 30 inches.
If you're serious about the height thing, take a desk you are comfortable with and set a proportionate height for the child. If you park yourself in a "regular" chair and sit up straight at your desk, where does the top of the desk hit you? Just at the bottom of your sternum? Where ever it hits you, aim for that point on the child and measure it. The ergonomics will be similar. Good luck.
Also, See these charts:
http://books.Google.com/books?id=9BM8Su0Oi00C&pg=PA11&lpg=PA11&dq=children%27s+furniture+sizes+height&source=bl&ots=KW7Uc0a_jX&sig=MHA7Ddqsq9V7KCyvPHA67rNPy3M&hl=en&ei=7tFhS-y0O4TosQOElsnCCw&sa=X&oi=book_result&ct=result&resnum=6&ved=0CB4Q6AEwBQ#v=onepage&q=children%27s%20furniture%20sizes%20height&f=false
The height of a desk depends on the age and height of the person it is intended for. A child's desk may only be three feet in height for example.
Height adjustable desk
id say about waist height =)
Ergonomically, the optimum height for kitchen counters is 3 feet, or 36 inches. This can vary however, as people of different heights would require different height counters.
Launch height is term used in aviation as optimum height for a release of missiles or bombs.
The SI unit used to measure the height of a desk is meters (m).
A heightometer.
You can pick the right desk height by knowing how tall you are. The most important is how comfotable you are and how much room will you need to work with.
The optimum height for a curtain rod is 2 to 3 inches above the frame.
Amazon.com offers a product called Dream Desk, which is a portable lap desk for kids. Also, check out the offerings of www.BuyLapDesk.com
The standard height for an adult study desk is 741 mm = 29¼ inches.
72 inches from tub floor.