What Causes a Piano to Go Out of Tune?

When you purchased your last car, you knew you’d have to maintain it.  You expected to fill it with gas on a weekly basis; you knew you’d have to wash it from time to time and you planned on an oil change every 3000 miles.  You also knew that – as your car aged – it would begin to wear out.  Over time, you’d have to put on some new tires; you’d have to replace the breaks and you’d have to swap the battery at some point.  From the beginning, you understood that such expenses were necessary to maintain your car’s performance and resale value.  Now imagine that your car was made out of wood.  How many more repairs and adjustments would you have expected to make?

A Wooden Car!

Imagine how much maintenance your car would require if it were made of wood.

Like a car, pianos have thousands of tiny components – many of which move or vibrate as part of their vital function.  …and, like neglected cars, neglected pianos will deteriorate to a point where they can’t be used (or sold) without costly repairs.  Put simply, it’s much less expensive to properly maintain your piano than to allow it to fall into disrepair.  Why, then, do so many piano owners neglect their instruments?

Oddly enough, most people don’t understand why pianos require regular maintenance.  It’s fairly easy for car owners to envision the “wear and tear” their breaks or tires experience, but piano “wear and tear” is often much more subtle.

New Pianos

New piano builders tighten each of the 230-some strings to a strain of nearly 200lbs each.  This means that the wood frame (reinforced with a cast-iron plate) is holding back a pressure of over 20 tons – that’s as much weight as about three and a half elephants!

Due to this extreme pressure, new pianos go through a period of adjustment or “breaking in” during their first two years of life.  Most notably, their wood components will adjust to the room climate, the piano’s strings will stretch significantly and the hitch pins (which hold the strings at the back) will develop grooves that prevent the strings from slipping around them.  By the end of the second year, most pianos will have settled into their proper tuning tension.  At this point, they will become much more stable and require less frequent tuning.

Piano Construction

As Grade 4 pianos flood the market with composite parts and low-grade wood, more and more piano owners are rediscovering the “buy nice or buy twice” principle.  While a “starter” piano might seem attractive because of its lower price, its particleboard and plastic construction won’t be able to withstand the 20-ton strain as well as an instrument made with top-grade components.  The piano will pull itself out of tune more frequently – thus making up for its lower purchase price with excessive long-term maintenance costs.

A piano with a solid wood frame and backposts (left) will withstand the 20-ton strain of stringing better than a lesser-made instrument (right).

Piano Placement

Even the best pianos will struggle with tuning stability, however, if they are poorly placed.  It’s never a good idea to position a piano in the path of direct sunlight, near an air vent, against an un-insulated outside wall or close to fixtures that directly affect a room’s temperature or humidity (such as a fire place, electric heater or fish tank).  These conditions create additional stresses on the piano and will push it out of tune quickly.

Environmental Changes

85% of the piano is made from wood – a porous material that is susceptible to changes in temperature and humidity.  During periods of increased humidity, the piano’s wood components absorb moisture and expand – pushing against the strings and forcing the piano out of tune.  As the humidity lessens, the wood dries out and shrinks – loosening the string pressure and pulling the piano out of tune.  Though these changes occur on a daily basis, major seasonal changes can cause significant variations in a piano’s pitch.  This is why most manufacturers recommend a minimal bi-annual tuning schedule.

Poor Tuning Technique

Of course, no matter how often a piano is tuned, no piano will remain in tune if it was improperly serviced in the first place.  A skilled technician will make sure that each string slides equally along its friction points during the adjustment process.  This prevents the wire from getting “hung up” and slipping out of tune later.  Inexperienced tuners can tighten or loosen a string much more drastically than necessary as they struggle to reach the desired pitch.  This makes achieving an equalized pressure across the string nearly impossible.   Thus, during play, the string will “shake loose,” equalize its tension and fall out of tune.  Tuning pins can also twist or bind during tuning.  A skilled tuner will take the time to “set” the pin and make sure it’s stable.  This prevents the pin from correcting itself later and pulling the string out of tune.  It is always better – and cheaper in the long run – to pay a few dollars more for the services of a skilledtechnician.

Each “note” may require up to 3 strings and each must be tuned and “set” properly to obtain the correct harmonics.


Even the best technicians can’t rewrite the laws of physics, however.  Variations in the piano’s environment will slowly and subtly pull it out of tune.  Whether it’s played regularly or not, every piano requires a minimum bi-annual tuning.  A neglected piano will have fallen so far out of tune that it will require a “Pitch Raise” prior to tuning.  A “Pitch Raise” restores the proper string tension so the piano can be fine-tuned.  A piano that has been neglected for more than a couple of years may require several tunings before it becomes stable at the correct pitch.  If neglected for a long period of time (the actual number of years varies by quality), the piano may lose its ability to be tuned.  At this point, a good technician will recommend restoring or replacing the instrument.

Heavy Use

Pianos are percussion instruments and even tuning once or twice a year can sometimes constitute “neglect” if an instrument is used heavily or in a very unstable environment.  Pianos used on the concert stage, in universities, in churches or in teaching studios will require four or more tunings per year.  This is also true of player pianos that are used heavily.  Every time the piano’s hammers impact the strings they increase the tuning stresses on the pins and the strings themselves.  Over time, the “hammering” will push the piano out of tune.  The more heavily a piano is played (especially if the piano is used for ear-training, performance, recording or play-a-long music) the more often it will need to be tuned.

Advanced Age

As people age, their bones become more brittle, their eyesight fades, muscles weaken and their bodies cease to function properly.  Pianos age too.  Over time, the wood frame will weaken, the curve (or “crown”) of the soundboard will flatten, the tuning pin block will shrink and the metal will fatigue.  Once these things begin to happen, the piano will finally lose its life-long battle against the 20-ton string tension.  This will happen slowly over a period of several years until a skilled technician recommends restoration or replacement.

A Cracked Tuning Pin Block

With age, this tuning pin block has cracked and weathered. It is no longer able to hold a firm grip on the tuning pins.


Very few people can actually tell whether or not their piano is in tune just by playing it.  The process of falling out of tune is so slow and subtle, it’s hard to detect.  The only way to make sure a piano holds its tune is to setup a regular maintenance schedule with a local (skilled) technician.  Understanding why a piano goes out of tune is just the first step.  The most important step comes next.


Now you should read “How Often Should I Have My Piano Tuned?” from The Gist Piano Blog.

Have specific questions for James or for the Gist Service Team?  Ask for help here!


2 thoughts on “What Causes a Piano to Go Out of Tune?

  1. Carol

    This is incredibly fascinating! I never knew all that stuff about how much pressure the piano is holding. Many thanks for making this knowledge so easily available!

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