Tom DeFerrari Piano Tuning and Servicing

Piano Tuning

Tuning a piano consists of adjusting the tension on each of the 250 or so strings on a piano. It may be surprising that there are that many strings, since there are only 88 keys. However, most keys on a piano have 3 strings, all tuned to the same note, while those in the bass section have 2 or 1 string per note. The piano tuner typically isolates all of the strings except 1 per note by using felt and rubber mutes.

Before the tuner can fine tune a piano, though, the piano must be fairly close to being in tune to begin with. If it isn't, then the piano tuner must do a rough tuning before doing the fine tuning.

Rough Tuning and the Piano's Pitch


The typical standard for a home piano is what is called A440 (but see A440, the Drifting Standard below for exceptions to this standard). This means that the A above middle C is tuned to vibrate at 440 cycles per second. All of the other notes are tuned relative to this.

For example, the A an octave higher than this middle A is tuned so that it vibrates at 880 cycles per second (ie, 2 times 440), the A an octave below vibrates at 220 cycles per second (ie, 1/2 times 440), the E above A440 vibrates at approximately 1 1/2 times A440, or 659 cycles per second, etc.

However, a piano can be in tune with itself, but out of tune with the standard tuning. In this case, the A above middle C may vibrate at, say, 438 cycles per second, the A an octave above at 876 cycles per second, the A an octave below 219 cycles per second, etc. In this case, the piano will be perfectly in tune with itself, but flat compared to other instruments.

This middle A can be at any value, even a note flat, but as long as the rest of the notes are exactly one note flat, the piano will be in tune with itself. However, it would be out of tune if played with another instrument that was tuned to the standard tuning

Whatever pitch that this middle A is tuned to is referred to as the pitch of the piano. If a piano is said to be one note flat, that means that the middle A is vibrating 415 cycles per second, which is the value that G# should have.

Often, especially when a piano hasn't been tuned in many years, the strings lose their tension, causing them to become flat. This can also happen due to excess dryness. Likewise, a piano can become sharp in pitch if the humidity is too high (see Piano Placement and Humidity Control). In either case, the tuner must rough tune the piano before fine tuning it.

Raising and Lowering the Pitch

Pitch Raising

When a piano is flatter than A440, the piano needs to be rough tuned before it can be fine tuned. This is because during the rough tuning, or pitch raise, the strings respond to the extra tension added to them by stretching and going a little bit flat again. In addition, the soundboard and bridges will respond to the extra tension by pushing back, and the result is that the strings don't stay at the pitch the tuner originally set them to (see Why a Piano Goes out of Tune).

In fact, during a pitch raise, the tuner must overshoot the target of A440. If a piano is 1/4 note flat, the tuner typically will rough tune it to 1/8 note sharp of A440, so that it settles at A440.

So, the pitch raise is done as a rough tuning, and when finished, the piano will be at A440 but out of tune with itself. Then the tuner can do the fine tuning.

Sometimes a piano is so far flat that it is only safe to raise the pitch in stages. This is partly due to the overshooting needed, and also due to the risks associated with adding too much tension at one time to the strings. For example, if the piano is a full note flat, the tuner would need to overshoot and raise the pitch to about 1/2 note sharp in order for the piano to settle at A440. Although pianos are designed to withstand some of this added tension of being sharper than A440 (since it is normal for a piano to go sharp due to excess humidity), there is a limit as to how far sharp it can go. In addition, if the strings are old or even a bit weak or rusty, any tension beyond what is necessary increases the risk of strings breaking. For this reason, when a piano is 1/2 a note flat or more, I prefer to bring it up to A440 in 2 or more stages, and on 2 or more visits. Even if the piano is brought up to A440 during one visit, the pitch raising should be done in stages, to avoid excess overshoot.

During a pitch raise, especially on a piano that hasn't been tuned in years, it is important for the tuner to flatten each string before pulling it sharp. This helps reduce the risk of strings breaking. The reason for this is that the string may have become 'stuck' at some of the pressure points it rests on, and if the tuner just pulls the string sharp, a single section of the string will take all of the added tension, and this can cause the string to break. By flattening the string first, it breaks free of these pressure points, and when pulled sharp, the added tension is distributed across the entire string.

Pitch Lowering

A very similar situation occurs when a piano is sharp of A440. The soundboard and bridges also respond to the lowered tension of the strings by pushing back, and so the strings don't stay at the pitch the tuner sets them to. There isn't the same risk of string breakage as during a pitch raising, but the piano still must be rough tuned before being fine tuned.

Uneven sections

Finally, even with a piano that is close to A440, the sections may be off. A piano can be at A440 in the mid section but sharp or flat in the treble or bass section. This occurs during changes in humidity, since when the soundboard contracts or expands, it does so to different degrees in the various sections (see Why a Piano Goes out of Tune). In this case as well, the piano must be rough tuned so that the sections are all at A440 before fine tuning.


Two very common situations occur in which someone will have a piano that is so flat that it needs several tunings.

This may put me at odds with some tuners who insist the piano student's ear will be trained incorrectly with a piano that is flat of A440, though in perfect tune with itself, but I disagree. The human ear accommodates itself to the overall pitch of a piano and notices only the relation of the notes to one another. If the piano is in tune with itself, this relationship will be correct. Most people, including most piano tuners, can't even tell what note is being played, or if it is at the correct pitch, without hearing some reference note first, though nearly anyone can tell when the notes are out of tune with each other. The one exception to this is people who have what is called 'absolute pitch', which means they can recognize what pitch a note has without hearing a reference note first. But since the A440 standard is man made, this whole argument about absolute pitch seems to me to be a misunderstanding, especially when you consider that this 'standard' has changed over the years, which I mention in the note below.


A440, the Drifting Standard

This standard, A440, has changed over the years, and continues to change. At the beginning of the 20th century, A435 was the standard, but it has crept up over the years until now it is at A440, and is creeping toward A442. This is due to many instrumentalists, such as woodwind or brass players, wanting a brighter sound from their instruments, which sound brighter and more penetrating if tuned at a higher pitch. In fact, for some current symphonies and orchestras, the standard they now tune to is A442. I rarely encounter piano owners who want their home pianos tuned to anything but A440, but if desired, it isn't a problem to do so.


How often to tune

Most manufactures recommend tuning their pianos at least twice a year. This is a good idea, and perhaps necessary for someone with a very good ear. For most people, and for the sake of the piano, once a year is usually good enough. Tuning once a year will insure that the piano stays at or near A440, and a large pitch raise will never be necessary.

When to Tune

Since changes in humidity (see Piano Placement and Humidity Control ) are what cause a piano to go out of tune, the best times to tune are just after a seasonal change. In the Centre County area, tuning a month or so after the heat comes on is a good idea since by then the piano should have dried out as much as it will for the year. This would typically be in late November and into December. The other optimal time for tuning is after the heat has been off for a month or so, which is typically safe by June.