Piano Tuning

What is Piano Tuning?

Piano tuning is the adjustment of the tension of each string in the piano to set its optimal pitch.  Increasing a string’s tension causes its pitch to rise and lowering its tension causes the pitch to drop.  Although (most) pianos have 88 keys, they usually have over 200 strings. Most notes actually have three strings, while the lowest notes have either two or one string per note. A tuning typically takes about 1 1/2 to 2 hours.

Pitch Correction

A piano must be very close to standard pitch (A440) before a fine tuning can be done.  When the pitch level of a piano is changed by more than 3 or 4 cents (there are 100 cents in a half step), the change in tension causes tuning instability. As the pitch level is changed, the strings that are adjusted early in the tuning will change as subsequent strings are adjusted. So, when the pitch level of a piano is very far off from standard pitch (A440), a quick rough tuning is necessary before a stable fine tuning can be done. This rough tuning is sometimes called a pitch raise or a pitch correction.

When a piano is significantly off from standard pitch (more than 25 cents flat or sharp), more than one rough tuning is necessary to provide a tuning exactly at standard pitch. ​I can help you decide, based on how you will be using the piano, if multiple rough tunings are necessary. Your piano should be maintained close to standard pitch. It was designed with standard pitch in mind, and it will sound its best at standard pitch. However, if your piano needs a significant pitch correction, it may make sense to make the correction over the course of a couple of regular tunings.

John tuning a piano

What makes a piano go out of tune?

Changes in humidity and temperature as well as use and time all affect tuning stability.

Pianos go out of tune primarily because of changes in humidity.  Pianos are mostly made of wood, which absorbs moisture from the air or releases moisture into the air until an equilibrium is reached.  When wood absorbs moisture from humid air it expands and changes dimension.  When wood releases moisture into dry air, it gets smaller.  You have likely noticed this change if you have ever observed wood floors through the seasons.  In the winter, when the air is dry from heating, the wooden slats itself get slightly smaller, and the cracks between the wooden slats grow bigger, a gap appears. The opposite is true in the summer.  As the slats expand with moisture, the gap disappears or grows smaller.  It is this same phenomenon that causes doors or windows to stick in the summer, but then free up in the winter. 

These same changes in the dimensions of wood in your piano cause it to go out of tune.  In particular, it is changes in the wooden soundboard that cause a piano’s pitch level to change.  When your piano is exposed to the dry air in winter, it goes flat, the pitch of the strings gets lower.  The opposite is true in the summer when moist humid air causes the pitch level to rise, your piano goes sharp. These changes in pitch don’t happen evenly throughout the piano.  They tend to be most pronounced in the tenor and lower treble. Since these changes don’t happen evenly, we perceive the piano as out of tune.

The humidity level in your home changes most dramatically because of heating.  In the winter, your furnace heats the air and dries it out. When you first begin heating in the late fall or early winter, there is a sudden dramatic change in the humidity level in your home.  Correspondingly, the tuning of your piano will change noticeably during this transition into the winter heating season, as your piano goes flat. Again, in the spring when you stop heating, the air in your home is no longer being artificially dried by your furnace.  Then the humidity level will rise and again the tuning of your piano will noticeably change, as your piano goes sharp. So your piano will go through two distinct cycles each year, with dramatic changes in the tuning of your piano taking place at the onset and end of the heating season.

Seasonal Changes in the piano pitch graphic. In dry months the piano will typically go flat and in the humid months the piano will typically go sharp
Use, temperature, and time also affect tuning stability.  Heavy playing can cause changes in the tuning, however, the better the tuner and the more frequently a piano is tuned, the less playing will cause changes in the tuning.  Temperature changes also cause the pitch level of a piano to change, however, with modest changes this usually happens relatively evenly across the piano, so the relative tuning may not be significantly affected.  Temperature changes during a tuning are problematic and a piano should be tuned at the same temperature at which it will be used. Finally, time has a gradual effect on tuning stability. Piano strings are at a very high tension.  That tension represents potential energy which wants to dissipate. As it dissipates over time, the pitch level drops and the piano goes out of tune. So, even without use and in a stable environment, pianos should be serviced with some regularity.

How often should I have my piano tuned?

Piano tuning is primarily for the player and the listener.  If your piano is being used, I recommend tuning it at least twice a year.  This will facilitate proper musical development of the ear and the most enjoyment of the instrument.  (Additionally I have frequently had customers remark that their piano is fun to play again following a tuning.)  Students who are practicing on an out of tune instrument are more likely to become frustrated and to quit. Regular tuning also allows your tuner to catch and correct any problems with the instrument early.

As previously discussed in the ‘What makes a piano go out of tune?’ section, the tuning of your piano will change dramatically twice a year, corresponding with the beginning and end of the heating season.  Tuning your piano twice a year will keep it reasonably well tuned throughout the changing seasons. (Music professionals, serious players, and institutions will usually have their pianos tuned even more frequently.) 

On the other hand, if your piano is not being used, I don’t believe it is necessary to have your piano tuned as regularly.  A piano will tend to drop in pitch over time. If you wait too long, there may be an additional expense for extra tuning when you do decide to have the piano serviced, but lack of tuning will not damage the instrument as some tuners say.  I recommend tuning a piano that is not being used perhaps every 2-3 years, or right before you know that it is going to be used (e.g. when your child is coming home from college for a holiday break).