Why Do Pianos Go Out of Tune?
- Aug 12
- 6 min read
Updated: 4 days ago
Every acoustic piano gradually goes out of tune—even when it is rarely played.
This is unsurprising when we consider the forces involved. Depending on its size and construction, a modern piano can carry approximately 16,000 to 20,000 kilograms of combined string tension. Its wood, metal, felt and leather components continually respond to this force, as well as to humidity, temperature, use and age.
Playing contributes to detuning, but in many homes the greatest influence is the changing climate around the instrument.
What Does “Out of Tune” Actually Mean?
Most piano notes are produced by two or three strings sounding together.
During tuning, these strings are adjusted to create one clean, unified tone. If they later move differently, the note begins to sound unstable or produces a wavering effect. This is often the first sign an owner notices.
However, the piano’s overall pitch can also rise or fall while the individual strings within each note remain relatively well aligned.
This distinction is important: a piano can still sound reasonably clean to its owner while the entire instrument has gradually moved below standard pitch.
Humidity Is Usually the Main Cause
The piano’s soundboard and other wooden components absorb and release moisture as the surrounding humidity changes.
When the air becomes more humid, the wood expands. When conditions become drier, it contracts. This movement changes the forces acting on the strings and affects their pitch.
Because the different areas of the instrument do not react identically, seasonal changes can disturb both the overall pitch and the relationships between individual notes.
Why Seasonal Changes Matter
In regions with contrasting seasons, indoor conditions can change considerably throughout the year.
During winter, central heating usually makes the air significantly drier. Once the heating season ends, humidity rises again. The piano therefore moves through a recurring seasonal cycle.
Based on our experience in Vienna, particularly stable results are often achieved when a tuning is scheduled approximately:
two weeks after the heating season begins, usually in October;
two weeks after the heating season ends, usually in April;
or at both points when consistently high tuning stability is required.
This gives the instrument time to adjust after the indoor climate has changed. The same principle applies in other cities with strongly contrasting seasonal temperature and humidity.
Why Regular Tuning Protects the Piano’s Overall Pitch
A tuning does more than clean up individual notes. It also keeps the whole instrument close to its intended pitch—normally based on A4 at 440 Hz.
Around this pitch, increasing A4 from 440 to 441 Hz, while proportionally raising the entire piano, adds approximately 75 to 90 kilograms of total string tension, depending on whether the instrument carries closer to 16 or 20 tonnes overall. A piano that has gradually fallen several hertz below pitch may therefore require hundreds of kilograms of additional tension to return to A440.
That amount cannot always be added while expecting one fine tuning to remain immediately stable. Changing the overall tension affects the soundboard, bridges, frame and the tuning of strings that have already been adjusted. A substantial correction may consequently require a pitch-raising procedure and more than one tuning pass. The Piano Technicians Guild similarly explains that significant net changes in string tension disturb the final result and require a dedicated pitch-adjustment process.
At VIA, we often encounter pianos whose individual notes have remained surprisingly clean for years. Their owners understandably believe the instrument is still in tune—which we take as a compliment to the previous tuning. Nevertheless, the entire piano may have gradually dropped by several hertz.
Returning it to standard pitch then requires considerably more work than maintaining it through regular appointments. What could have remained a normal annual tuning may instead require several passes or follow-up tunings, making the process more expensive for the owner.
Does Playing Make a Piano Go Out of Tune?
Yes, although it is not always the main cause in a private home.
Repeated hammer strikes place continuous forces on the strings. Intensive practice, forceful playing, lessons, rehearsals and performances can gradually disturb the tuning, particularly when the instrument is already reacting to climatic changes.
This is why heavily used teaching, concert and recording instruments require more frequent tuning than an occasionally played home piano.
Why Action and Hammer Maintenance Also Matter
Tuning stability should not be considered completely separately from the piano’s mechanical condition.
The action determines how the hammers approach and strike the strings. As hammer felt wears, the originally rounded striking surface becomes flatter and develops increasingly deep string grooves. The strings may then no longer be struck as cleanly and evenly as intended.
Regular action servicing, hammer alignment and reshaping help ensure that:
the strings within each note are contacted evenly;
the pianist does not need unnecessary force to produce the desired response;
the hammers rebound correctly;
the tuning remains cleaner under regular playing.
Hammer wear does not replace climate as the primary cause of detuning, but in our experience, allowing hammers to become severely flattened or deeply grooved can reduce how well an otherwise stable tuning withstands intensive use. Yamaha likewise notes that fixed hammer positions gradually create grooves and flatten the striking surface, making hammer and action maintenance important parts of preserving a piano’s performance.
Why New and Freshly Restrung Pianos Need More Attention
New strings do not immediately remain completely stable under tension. They stretch and settle gradually.
With newly manufactured pianos, much of this initial stabilization is normally handled by the maker, distributor and showroom technicians before delivery.
The effect is particularly important after a piano has been freshly restrung during restoration. Several additional tunings are generally required during the first year before the instrument reaches greater stability.
Because a restored piano usually returns directly to its owner, clients should clarify whether these settling tunings are included in the restoration price. At VIA, the necessary first-year tunings following a complete restringing are included in our restoration service.
Does Moving a Piano Make It Go Out of Tune?
Moving can affect a piano, but usually not because transportation simply shakes the strings loose.
The greater influence is often the change between the previous and new environments—for example, moving from a climate-controlled showroom into a strongly heated apartment.
Once the piano begins adapting to the new temperature and humidity, its pitch may change. A permanently relocated instrument should therefore normally be allowed to acclimatize before its tuning is finalized.
Can Technical Problems Cause Tuning Instability?
A healthy piano should hold a professional tuning reasonably well under suitable conditions.
If it becomes badly unstable shortly after every appointment, possible causes include:
loose tuning pins;
deterioration of the pinblock;
damaged or unstable strings;
bridge or structural problems;
severe climatic fluctuations;
incomplete stabilization after restringing;
worn or poorly regulated action components;
improper hammer alignment or condition.
Repeatedly retuning the instrument without identifying the underlying problem may offer only temporary improvement.
How Can You Help Your Piano Stay in Tune?
No acoustic piano remains perfectly tuned indefinitely, but owners can improve stability by:
arranging regular tuning rather than waiting several years;
keeping humidity and temperature reasonably consistent;
avoiding direct heat, sunlight and air-conditioning;
allowing a relocated piano to acclimatize;
following the settling schedule after restringing;
servicing the action and hammers before wear becomes excessive;
investigating unusually rapid instability.
Key Takeaways
A modern piano can carry approximately 16,000–20,000 kg of string tension.
Humidity and seasonal changes are usually the main causes of detuning.
Individual notes may remain clean even while the piano’s overall pitch falls.
Raising the whole piano by one hertz around A440 adds roughly 75–90 kg of tension.
Regular tuning prevents large, costly pitch corrections.
Action regulation and properly shaped hammers help a tuning withstand regular playing.
New and freshly restrung instruments require additional settling tunings.
Rapid instability may indicate an environmental or technical problem.
Why VIA?
At VIA – Piano & Arts Center, we do more than restore the correct pitch. We consider why the piano has changed and whether its stability is being affected by its environment, overall pitch, action condition, hammer wear, transportation or previous restoration work.
During every tuning appointment, we also assess the instrument’s general technical condition. If smaller issues can be resolved during the visit—such as a squeaky pedal or a sluggish key—we take care of them at no additional cost.
Our goal is to help each piano remain stable, expressive and reliable rather than treating every tuning as an isolated appointment.
Book a Piano Tuning in Vienna
If your piano sounds out of tune or is due for regular maintenance, VIA offers professional piano tuning and servicing throughout Vienna.
