Piano Pages
How often should a piano be tuned?
Steinway recommend tuning at least three or four times a year. This is a recommendation for an instrument that is one of the best in the world. Lesser instruments will not necessarily hold their tuning as well as a Steinway. Many "domestic" piano owners compromise and have the piano tuned at least every six months. For professional or teaching use, four tunings a year would not be unusual.
Concert use
A piano used for public performance should be fine tuned soon before every performance, but it should already be in good stable tune before this, or it may not be as stable during the performance as it could have been. Never plan just one tuning for an important concert on an instrument that is not known and/or trusted.
A concert tuning should not be a tuning on an instrument that has missed previous regular tunings.
Never used piano
A piano that is never used should still be regularly tuned.
What happens if tunings are missed
Missing tunings can cause the piano to fall out of tune beyond the limits from which it can be readily brought into stable, fine tune. In other words, if the piano misses tunings, one tuning will not necessarily bring the instrument back to its optimum state of stability and fine tuning.
If the instrument has lost its state of optimum stability, it will go out of tune faster than otherwise, which means it now needs to be tuned again sooner than normal. If this is not done, the scenario ranges from :
At best - the piano may take several tunings to regain optimum stability.
At worst - the piano will progressively deteriorate - this means the optimum standard of fine tuning and stability of which the instrument is capable, itself deteriorates.
Unlike violins and 'cellos, all pianos deteriorate in time. This long term deterioration is considerably accelerated by missing tunings.
A suitable tuning interval
Remember that concert pianos of the highest quality, are tuned before every performance. The normal 6 monthly cycle of tunings for 'domestic' instruments does not suggest that pianos stay in fine tune for this long - 6 months may not be appropriate where the demands or expectations for fine tuning are higher than for the average 'domestic' situation.
See also this page.