The piano was manufactured to be tuned and maintained at A440 pitch. This is the internationally accepted standard and the standard for which all pianos are engineered.
Unfortunately, no matter how expertly a piano is tuned, the changes in the temperature and humidity, and the nature of the piano’s construction constantly conspire to bring it off pitch.
Your piano has been designed and built so that in normal use and under normal conditions it should need only periodic tuning. We recommend that your technician be called at least two or four times a year. To put the matter of tuning into perspective, remember that a concert piano is tuned before every performance, and a piano in a professional recording studio, where it is in constant use, is tuned three or four times each week as a matter of course.
Tuning is an art practiced by skilled professionals and under no circumstances should anyone other than a professional be allowed to tune your piano.