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How often should I tune my piano?

  There are many different answers to this question.
New pianos should always be tuned according to the manufacturers recomendations. That could be up to 3 or 4 times per year for the first 4 years depending on the manufacturer.  After that, pianos should be tuned at least once a year and pianos that are played frequently could require tuning more often than that. 
There is not one answer that will be true for all pianos but by tuning your piano on an anual basis you can generally avoid have to have the pitch raised when you do finally decide to have it tuned.