Nev G,
To my knowledge, there is no "automatic" method of "compacting" a spreadsheet in the terms you describe - i.e. within the spreadsheet itself.
I believe the best method to "compact" a spreadsheet, is to do delete any unused columns and rows. Such rows might have been "formatted" in the past and are no longer in use, and if so, will consume memory and file space.
The quick method of determining the "last cell in use" on a worksheet is to use the <End> <Home> method. After hitting the <End> key, followed by the <Home> key, your cursor will go to the cell which is at the "juncture" of the "last column" in use, and the "last row" in use.
Then manually determine the "end point" of your "valuable" data. If there is a "difference" between the two "end points", then you have identified an area where you can "compact" the worksheet. Do this by deleting those columns to the right of your "valuable" data, and by deleting the rows below your "valuable" data.
Hope this helps. Please advise.
Regards, ...Dale Watson dwatson@bsi.gov.mb.ca