In a nutshell, the term enharmonic equivalent means notes that sound the same as one another but are named or “spelled” differently. (This concept can also be extended to include intervals and scales.)

The musical alphabet consists of seven main notes represented by seven letters: A-B-C-D-E-F-G. However, you might be aware that there are actually twelve possible notes (half steps) in an octave. 

For example, on the piano, if you count every key (white and black) from A to A, C to C, or any other octave, you will count 12 keys. Similarly, on the guitar, you will reach “E” again on the low (or high) E string once you get to the 12th fret. Adjacent frets on a guitar are half steps, as are adjacent keys on a piano.

In order to name all of these notes, we have sharps (#) and flats (b) in music notation. To “sharpen” a note means to raise it one half step—so A# is one half step above A. (That would be the key between A and B.) Similarly, to “flatten” a note means to lower it by one half step—so Bb is one half step below B. (That would also be the key between A and B…)

And here, we meet the enharmonic equivalent

 

BREAKING DOWN THE ENHARMONIC EQUIVALENT

In the example above, I moved up a half step from A to reach A#, and I also moved back a half step from B to reach Bb. Not only do these two notes sound identical, they are the same. (They are both the note between A and B.) So, yes: one key on a keyboard actually represents two notes – and so does one fret on a guitar.

These 2-notes-in-one are called enharmonic equivalents because they sound the same—indeed, they are the same note—they just go by different names depending on the situation. G# is the same as Ab, C# is the same as Db, F# is the same as Gb, and so on. *Note: B to C and E to F are separated by half steps, so B#=C, and Cb=B, etc.

 

WHY USE ENHARMONIC EQUIVALENTS?

The reason we use two different names for identical notes comes from the way we conventionally discuss music theory. Traditionally, if one is composing music in some key, it is only acceptable to have one “kind” of each note name. It sounds confusing, but here’s an example: 

In the key of G major, our notes are G-A-B-C-D-E-F#-G. We name the seventh note F# because if we named it Gb, we would have two different types of G (G and Gb), and that is a no-no. We want only one kind of each note (by “kind” I mean natural, sharp, or flat) to keep things organized and logical. As is always the case in music, there are exceptions, but this convention should be observed whenever possible.

That being said, sometimes it’s easier to think of a note as being the sharpened version of the note as opposed to the flattened version of another (and vice versa), even if it is not notated as such. Consider that, generally, if we are moving up a scale or melody, it is easier to think of sharpening notes because you simply move up from a note you are already on. Similarly, if we are moving in a downward direction, it is often easier to think of some notes as being flattened. (Either notation would technically lead you to the correct note, but sometimes it’s easier for our brains to process them this way.)

Hopefully this helps to make sense of a somewhat tricky concept. Rock on!