A=440 and Your Piano:
An Explanation of “Standard Pitch” 

Most people, somewhere and at some time, have heard the term A=440. They may even know it has something to do with music. But most people, even musicians who should know, have little concept of what A=440 really means.

The explanation is actually very simple. A=440 is the standard that has been designated for the note “A” above middle C. In other words, that string (or reed, or electronic pulse, or whatever else depending on the instrument) should vibrate at exactly 440 vibrations per second (or 440 Hz). And for nearly 100 years, this standard has been accepted almost universally for most music in the English speaking world, and world-wide with some exceptions.

The Importance Of “A=440” in Piano Tuning

But why all the hubub about a sound wave too fast to count, anyway? After all, a piano could be tuned considerably above or below A=440, provided the notes are all in correct proportion to each other. And the percentage of people, even musicians, who have that mystical gift of “perfect pitch,” and thus could even tell if “A” is really “440,” is rather small. So what’s the big deal? Glad you asked. Here are a number of answers that most good musicians would endorse: 

1. The piano was designed to be tuned at standard pitch.

The back braces, cast iron plate, soundboard, and bridges assume that each string will be kept tuned to its proper tension–somewhere between 150 and 200 pounds each. It is true that many older pianos were designed to be tuned lower, such as at A=435. But even A=435 is so close to A=440 as to be almost imperceptible. Tuners routinely find “A” on neglected pianos at below 420 vibrations per second–which is just about the correct frequency for A-flat.

2. The musical establishment has accepted A=440 as its standard

Thus, for the most part, all the music heard on radio, TV, and recordings, as well as the set pitch of all fixed-pitch instruments such as electronic keyboards, is at A=440, and has been so since about 1936. 

3. Whenever any serious piano instruction or study is taking place, standard pitch is extremely important for proper ear training.

This is especially important with children, whose natural musical gifts may be far beyond what the child can actually perform, and beyond what their parents may be aware of. Thus, the child could have a gift of perfect pitch which hasn’t yet become evident, and so may become thoroughly confused and distracted by a piano which is tuned below pitch. The bottom line is that a piano tuned to a pitch other than A-440 is simply not in tune!

4. Neglecting to keep piano tuning at A=440 is risky for your piano.

It could result in serious problems, especially if and when the owner tries to get the piano back in tune. These problems include broken strings (even one or two can be expensive to replace); cracks in the soundboard, bridges, or even metal plate because of changes in string tension; and the high cost of the multiple tunings often necessary to get the piano back in tune.

5. Piano tuning at standard pitch is important because it keeps the piano tuned at some unchanging standard.

A piano simply tuned to itself (i.e., leaving “A” at 435, 430, or wherever the tuner finds it) will continually drop in pitch just because of changes in weather and other factors, until eventually, serious problems could result.

The Job Of Pitch Raising

Let’s assume that your piano, for some reason, is considerably below standard pitch when your tuner arrives. We’ll assume it’s due to someone else’s neglect, of course. Exactly what has happened within your piano? 

Realize first that an in-tune piano is a dynamic arrangement of over 200 vibrating strings, each one having been tuned to its proper pitch by being tightened to nearly 200 lbs. (To grasp the significance of this, imagine a 200 pound man hanging from each string.) The total tension exerted on the structure of the piano, with approximately 200 strings at 200 pounds each is 40,000 pounds, or 20 tons! To hold all of this tension, the piano’s structure has been reinforced with several thick wooden back braces (visible from the back of the piano), a heavy cast iron plate (weighing 200-500 pounds), and threaded metal tuning pins pounded into a dense hardwood pinblock (see illustration below).

Backbraces in an upright piano

Plate in a baby grand piano

Now here’s the problem: in the process of slipping out of tune below pitch, each of your strings will have loosened to considerably less than 200 pounds. For purposes of making the point, let’s suppose they have all slipped to 180 pounds each. Multiplying the 20-pound differential by 200 strings, yields a total drop in tension of 4,000 pounds, or over two tons less. Now, assuming this drop has not caused any structural problems in the piano (which is certainly possible), consider just the challenge to a tuner trying to set things right. 

This may be difficult to picture, but try to imagine your piano as a large archer’s bow, with the strings acting as the bowstring. Now imagine pulling on the bowstring and stretching it: what happens to the bow? Though it offers some resistence, it bows inward, which in turn makes the string somewhat looser than it would have been if you had pulled it out with the bow being totally firm.

The piano, like the bow, is somewhat flexible also, despite all the strength built into its back structure to support its 20 tons of string tension. Thus, when the tuner begins to tune those below-pitch strings, each string he tunes causes the back structure to “give in” slightly. By the time he has tuned all 200-or-so strings, the piano has “bent” considerably, and thus is out of tune by the time he finishes the job. Even though most good tuners will allow for this drop in pitch by tuning each string higher than its correct pitch, it is impossible to do this with precision because each piano reacts to the pitch-raising differently.

Upright Piano, cutaway view,
before and during pitch-raising

Before (above):  As the strings
loosen up 
over time, the back
settles in to the lower
tension, and is resting 
comfortably there.

After (above):  The increased
tension from 
tightening the
strings causes the 
back structure
to give in slightly, 
thus loosing
the strings which have 
been tuned.

Practical Considerations

The bottom line, then, is that a piano that is considerably below pitch must be tuned more than once if it is to be put properly back in tune.

One question that often arises is whether or not a given neglected piano can even be brought back to standard pitch. Most technicians will tell you that a majority of them can. The exceptions are the following:

1. Pianos with old, tired strings that break when pulled up to pitch. These pianos are the exception rather than the rule. But if replacing all of the strings is not a reasonable option (this can be an expensive job), such pianos are best left below pitch to live out the remainder of their lives with dignity.

2. Pianos with excessively loose tuning pins. Some degree of looseness can still withstand the added tension of standard pitch, but at some point the pins must either be treated with a pin-tightening solution, or, if the tuner feels that will not be effective, left below pitch.

3. Pianos with obvious structural damage. These cases, which include such conditions as a cracked pinblock or plate, or split back braces, are very unusual and in most cases signify that the piano is Dead At Any Pitch (D.A.A.P.).

The conclusion of the whole matter? Remember that all of the above problems, for the most part, apply only to the neglected piano. With regular tunings and maintenance (at least once a year, and preferrably twice), your piano should remain near standard pitch and live a happy life.