Air Conditioning - How Large of an AC unit for workshop??

I have a 14x28 shop 2x4 walls so Iam looking at r 11 or so in the walls and maybe I can get a r 25 in the cieling. It is a wide open space with 8 foot walls.
I plan to put two ceiling fans to move the air. I need to find out what size window or wall unit to use. This shop is used for sewing so it needs to stay cool.

There are WAY too many variables to even begin to get into on a message board. I suggest you do a manual J load calculation. Here is a link to a site where, for about $50, you can download & run the calculation. http://hvaccomputer.com.

So I have have a heating and air buddy let him do the calc Huh?

If you can get it done for free (or a case of his favorite beverage, etc), go for it.

Yeah I would be careful with a area where a large quantity of fiber type materials are stored and used. You do not want this area to become very humid, go ahead and have the manual J done and then make sure you get a variable speed unit that utilizes a humidstat. It sounds like a new construction are you considering a residential fire suppresion system? the sprinkler systems are getting more and more popular and the cost is usually only around a buck per sgft the technology has advanced a bunch, virtually no chance now exists for accidental water spray, boy that would add some humidity even a variable speed unit might have trouble with LOL