Tuning fork
A tuning fork is a U-shaped metal bar that, once struck, gives off almost nothing but its fundamental, usually A4 at 440 Hz. It serves as a pitch reference for tuning.
- Usual note
- A4 = 440 Hz (standard pitch)
- Sound
- an almost pure tone, hardly any overtones
- Striking
- on the knee or the heel of the hand, not on a hard edge
- Alternative
- an electronic tuner that shows cents
A note nothing disturbs
A string vibrates in many partials at once, see the harmonic series. A struck tuning fork behaves differently: the two prongs swing against each other, and the stem in the middle hardly moves. The higher notes fade quickly, and what is left is the fork's natural frequency. This single, calm note makes a good yardstick.
The fork's note and its octaves
The standard fork sounds A4 (marked) at 440 Hz. An octave lower is 220 Hz, an octave higher 880 Hz. The fork's sound is almost a pure tone, without the overtones that strings and voices bring with them.
How to tune with it
You strike the fork and press the stem against a resonating body, such as the body of a guitar, and the note gets louder. That is resonance. Then you compare it with the string that is supposed to give the same note. If the two differ, you hear a beat, which slows down as you bring them together and disappears. How the number of beats relates to the difference is explained under interference.
A tuning fork measures nothing: it only gives you a note. An electronic tuner, by contrast, shows how many cents a string is off. For the ear, though, the fork is ideal, because there is nothing to read off.
Common mistakes
- Striking the fork on hard edges: This produces extra noise and overtones.
- Assuming all forks are 440 Hz: There are other reference pitches, see standard pitch.
- Touching the prongs: This damps the note.
Continue on Maikstrings
Related terms
Standard pitchNatural frequencyResonanceBeatingCentPitchVibrationIntonation
Editor: Maik Krohm · reviewed on 3 October 2026
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