440 Hz Tone - Concert Pitch A4

For centuries, "A" meant something different in every city - baroque ensembles played near 415 Hz, Verdi-era Italy pushed for 432 Hz, and some late-romantic orchestras crept above 450 Hz, straining singers' voices. An international conference in London settled on 440 Hz in 1939, and ISO 16 formalized it in 1955. Today virtually all tuners, keyboards, and orchestras default to A4 = 440 Hz.

The choice was a practical compromise near the middle of the pitches then in use - there is nothing acoustically magical about 440 itself. Some European orchestras still tune slightly higher (441-443 Hz) for a brighter sound, and period-instrument ensembles deliberately tune lower for historical accuracy.

Play the tone above and tune your instrument's A until the two sound identical. When you are close but not exact, you will hear slow "beats" - a rhythmic wah-wah-wah as the two pitches interfere. Tune until the beating slows down and disappears entirely: that is perfect unison, accurate to better than 1 Hz by ear alone.

Guitarists tune the A string (A2, 110 Hz - two octaves below this tone) by matching its character rather than its exact pitch; the octave relationship is easy for the ear. Violinists and violists tune their A string (A4) directly against it. For all 12 chromatic reference notes across several octaves, use our pitch pipe, or our instrument tuner for instrument-specific presets.

You may have encountered claims that 440 Hz is harsh or was maliciously imposed, and that 432 Hz is the "natural" alternative. Historically, 440 Hz won standardization through committee pragmatism, not conspiracy. Audibly, the difference is about a third of a semitone - real but subtle. Play this tone and then our 432 Hz tone back to back and judge for yourself.