Dunno, but an easy way to figure it out would be to paste the text of your statement into Microsoft Word, then click on File > Properties > Statistics.
Getting the character count of my document isn't the issue; I don't know how wide their margins are, so I don't know how many characters their "page" holds vs. a typical Word document.
We were told that the personal statement is printed out for residency programs in 10 font Courier New Text with 1/4'' margins on the L and R and 3/4'' margins top and bottom. I think it is roughly 750 words or so.