Tuning Fork — A440 (Concert Pitch)
440.00 Hz
Nearest note: A4 in standard tuning
The international standard for concert pitch: the A above middle C.
How well is this supported?
Measured directly, or defined by a published standard.
This is a note in standard tuning. Its value is set by definition, not measured.
The button plays a plain tone. Start with the volume low.
About this number
A tuning fork that sounds A4 = 440 Hz, the international standard for concert pitch (ISO 16:1975). Not every orchestra tunes to it: many use 442–443 Hz. Some musicians prefer A = 432 Hz.
History
Recommended at an international conference in London in 1939. Issued as ISO Recommendation R 16 in 1955, and as the standard ISO 16 in 1975.
Facts
- Frequency
- 440.00 Hz
- Wavelength in air (20 °C)
- 78.0 cm
- Nearest note
- A4 in standard tuning
- Kind of statement
- Musical standard
- Filed under
- Instruments & gongs
Sources
- ISO 16:1975
The international standard that sets A4 at 440 Hz.
ISO 16:1975, Acoustics — Standard tuning frequency (Standard musical pitch). Supersedes ISO/R 16:1955.
More about the pitch
The same note in every octave
Each step doubles or halves the frequency. Tap one to hear it.
Entries close in pitch
Within 35 cents of this tone, in any octave. A cent is one hundredth of the step between two neighboring piano keys. Being close in pitch does not mean two things are connected.