Walters Piano Service

Pianos at the very least should be tuned annually. New pianos need to be tuned as much as four times per year because of stretching strings. Really, you should let your ear be your guide. If more than annual tunings of your piano are needed to keep you satisfied musically, by all means do so. Concert artists have pianos tuned before every performance. It's in their contract. A piano actually can go out of tune to a degree within hours.

Temperature and humidity are what affect the tuning stability of your piano. It doesn't matter whether your piano is played or just sits there, it will go out of tune. The longer a piano goes without tuning, the harder and more costly it will be to put it back into stable condition at A440, international pitch.