Why does a piano go out of tune?

There are several factors that may cause a piano to go out of tune, but the main culprit is generally climate. The piano’s soundboard is made of wood, which will expand in humid weather, and contract in dry weather, altering the pitch of the piano. Changes in humidity are more significant than changes in temperature, but the more stable all climate conditions are kept, the more stable the piano will be.

Moving a piano (introducing a new climate), new piano strings (as they undergo a stretching process), and loose tuning pins (common on older pianos) are other common causes of tuning instability. Playing a piano very loudly can contribute as well, but is usually not a significant factor.

What is a “pitch raise”?

When a piano is at least a quarter of a tone sharp or flat of standard pitch (A440), it will need a pitch raise. A piano has about 215 strings, and when they are all significantly stretched (or slackened) during the tuning process, the pressure change to the piano’s structure will cause it to go immediately back out of tune. Therefore, a very out of tune piano will first need to be rough tuned to bring it to standard pitch before it can be fine tuned. Both tunings can be done in one visit.

Having your piano tuned every 6 months will eliminate the need for a pitch raise and increase the amount of time your piano will stay in tune.