The intervals between keys on a piano are named based on the number of keys (including both black and white keys) they encompass. Here are the common interval names:
a) Minor Second (m2): This interval spans one key, including both adjacent white and black keys. For example, C to C# or E to F.
b) Major Second (M2): This interval spans two keys, including both white and black keys. For example, C to D or F# to G#.
c) Minor Third (m3): This interval spans three keys, including both white and black keys. For example, C to E♭ or G to B♭.
d) Major Third (M3): This interval spans four keys, including both white and black keys. For example, C to E or A to C#.
e) Perfect Fourth (P4): This interval spans five keys, including both white and black keys. For example, C to F or D to G.
f) Augmented Fourth / Diminished Fifth (A4 / d5): This interval spans six keys, including both white and black keys. For example, C to F# or F to B♭.
g) Perfect Fifth (P5): This interval spans seven keys, including both white and black keys. For example, C to G or A to E.
h) Minor Sixth (m6): This interval spans eight keys, including both white and black keys. For example, C to A♭ or D to B♭.
g) Major Sixth (M6): This interval spans nine keys, including both white and black keys. For example, C to A or E to C#
h) Minor Seventh (m7): This interval spans ten keys, including both white and black keys. For example, C to B♭ or F to E♭.
i) Major Seventh (M7): This interval spans eleven keys, including both white and black keys. For example, C to B or G to F#.
j) Perfect Octave (P8): This interval spans twelve keys, encompassing all the keys within an octave. For example, C to C or D to D.
These interval names are fundamental in understanding and describing the distance between notes on the piano keyboard, as well as in music theory and composition.