A is a musical note equivalent to 440 Hz in typical A440 tuning.
It is the sixth note of La and the tenth semitone of the fixed-do solfège.
[1] However, tuning has varied over time, geographical region, or instrument maker.
Historical examples exist of instruments, tuning forks, or standards ranging from A-309 to A-455.3,[2] a difference of almost six semitones.
A7 is a few pitches lower than C8, the highest note on the standard piano.