Pitch Raise Percentage

[Philip J Ryan]

I did a pitch raise on a 30 cent flat piano yesterday with my SAT (25%) 
recalculating it several times along the way.  I ended up with a very sharp 
piano.  After bringing it down with the fine tuning, it crept back sharp 
again and I ended up leaving it a little sharp. (Not a bad thing)  However, 
does anyone have a rule-of-thumb for calculating a pitch raise percentage 
that will leave it close to A-440? Are there variables to be considered 
such as size of piano, age, condition of piano/strings, etc. other than the 
obvious?   I would love to hear what others do in this situation.

Phil Ryan