What’s the Difference Between a Scale and a Key?

After reading this post, if you are not 100% confident to explain keys and scales to a friend, please leave a comment with your question.

If you’re looking for a quick fix, skip to the red letters.  

What’s the Difference Between a Scale and a Key?

You may have hear the phrase shouted your way “we’re in the key of C.” Or maybe you’ve toiled over the two octave C scale only to wonder, why am I doing this?

But what is the difference between keys and scales?  Keep reading to find out.  But first, a visit from geometry class past.

On squares and rectangles: Keys and scales are completely different and very, very similar.  Consider your geometry friends the square and the rectangle.  A square falls under the category of rectangle because it has two pairs of equal and parallel sides.  However a square is a very specific type of rectangle.  The rectangle has a more broad definition and the square, a more specific definition.  The key has a more broad definition and the scale a more specific, strict definition.

So a rectangle and key are more broad, and a square and scale are more specific…


SCALE: A series of notes played in order

A scale uses specific notes. A “C Scale” always includes only C D E F G A B.  No #’s or b’s.

Music Theory Explained

Music Theory Explained

KEY: The tonal center of the song.

Okay, the definition of “key” is more abstract than that of “scale.”

We are in the key of C = we are using the notes in the C Major scale. However, we could also borrow notes from other scales, without changing the key.

Let’s Compare:

SCALE:  use ONLY the EXACT notes in the scale going from a letter to the next of the very same letter (CDEFGABC)

KEY: use scales, and accidental, and creative license, and whatever else, as long as the scale you are using remains the tonal center of the song.  Meaning it sounds like home when you return to the first note of the scale.


For Example, the Key of C:

  1. Uses a C scale
  2. Has no b’s or #’s in the key signature and…
  3. The C chord feels and sounds like home base.  In other words, your ears are comfortable with the song ending on the C chord.  (It is possible for the song to use the notes of the C Major scale but the A sounds like home base.  This is possible because C Major and A Minor scales share the exact same notes.  If the A sounds like home base and it used the same notes as the C Major scale, it’s actually in the key of A minor.)

To Recap:

A Scale (a NOUN) is a specific set of notes played in order

The Key (an ADJECTIVE) describes the tonal center of the piece

Disclaimer: Every musician will not agree.  While the definition of scale is very …defined…the definition of a “key” is much more loose and therefore creates some conversation among musicians. 


What’s your favorite key to play in? Let us know, and check out what other’s are saying.










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