When asked, “How often should I tune my piano?” The answer given was “Whenever it needs it.”
The frequency of the tuning depends greatly on the individual using the instrument. Some people have very critical hearing and can notice the slightest variations in tuning. Others have little natural ability to hear when the instrument is greatly out of tune. So, thankfully, there are some guidelines…
The accepted tuning schedule that is touted by most manufacturers and professional technicians is 2 times per year. This schedule will keep most pianos functioning at a high level of performance for most players. This schedule will account for the atmospheric changes from season to season.
I recommend that a piano be tuned 2 times a year, but if not twice, then AT LEAST once a year as a minimum basis. I do not recommend tuning any less frequently than that.