I'm a beginner guitar player and I am just now foraying into theory / keys / chord progressions. I've seen this grouping of chords in several songs:

E - C#m - G# (or Ab?) - A (Where Is My Mind - Pixies)

C#m - G# - A - E (Say It Ain't So - Weezer)

or, similarly, a step up:

Dm - A - A# (or Bb?) - F (Luckiest Man - Wood Brothers)

So anyways, what key would these songs be considered to be in? Also, while on topic, would you consider those chords in the first two patterns to be G# or Ab, and why? Keep in mind I am very new to theory, so please explain like I'm a 5 year old.


There is rarely one unique scale (key) that a given set of chords will fit into; usually, at least two scales will fit pretty well. Another way to see this: the difference between two scales can be a single note that is different; but if the distinguishing pitch is never played during the song, then which scale is correct? The answer is, whichever the composer chose. (E.g. how can you distinguish the key of C from the key of G if neither an F nor F# is played?)

Having said that, for much of contemporary music, it is often possible to figure out which key was "probably the intended key." One easy heuristic is that the first chord of a song is usually the tonic (i.e. it matches the key), or sometimes it is the M5.

A more reliable method, is simply to lay out each note of each chord in the progression on a keyboard diagram or staff and see which scale fits best, preferring a scale where the tonic is played more often.

Here's a web app which tries to narrow that down; I couldn't get it to work, but maybe you'll have better luck.

  • 1
    To distinguish a key - often the 1st chord in the 1st full bar, as the anacrusis will be V. Or, the place in the piece where it feels like it's come home, like the beginning of the part after the bridge, or the end. Not always, but often. – Tim Jun 14 '16 at 7:28

The way I was taught to determine a song's key is fairly straightforward: You list the pitch class (all the known pitches in a melody) and use that to determine the key. In this case, we have a collection of chords instead of a melody, so let's use that. I'm doing this more or less in my head, so please consider this a rough draft and let me know if there are any errors!

A bit of theory:

A song's key can be thought of as, rather than a list of what pitches are allowed, a starting place. There will often be accidentals - notes outside the key. What we want to do is find the key that's generally the center of the song. But if most of the pitches are in the key, it's probably right.

Theory is meant to describe music, and music is composed based on what sounds good. We use the theory aspect to (1) write stuff down, and (2) describe and maybe understand the music.

The difference between A# and Bb:

I'll do what I can to keep this simple, but feel free to skip ahead.

In the tuning system we use, they're enharmonically equivalent (read: The same thing for our purposes) but there are other tuning systems where this wasn't the case. For now, just remember that you want to have one note in a key for each named note and no more.

C major:


A major:

A B C# D E F# G#

E Major:

E F# G# A B C# D#

On to the music:

E - C#m - G# (or Ab?) - A (Where Is My Mind - Pixies)

Gives us the following pitches:

B C C# D# E G#

I think this puts us in the key of E major. (You've probably noticed that there's a C and a C# here - right you are. C is an accidental note, outside of the key. This can make the G# chord want to resolve to A.)

C#m - G# - A - E (Say It Ain't So - Weezer)

Gives us:

A B C C# D# E G#

Again, the C is an accidental, and outside of the key. Even more interesting, the B, C, and C# are a short chromatic run. Cool! Listening to the song, the key sounds like C-sharp minor to me. (C#m is also the relative minor of E major - that means the keys have the same notes but start from a different point.)

[Note: The version I can find on youtube are in Cm, the relative minor of Eb major, but I'm using your original key here.]

Dm - A - A# (or Bb?) - F (Luckiest Man - Wood Brothers)

A Bb C Db D Eb G E F

I'd guess this is in D minor (relative of F major, a key with one flat note), and I'd notate it that way. You'll note that the B flat chord sounds out of place, and resolves nicely to the F, it keeps the chord progression moving forward well.

Playing notes in the D minor pentatonic scale works well over this progression, and you can't go wrong playing D here, and A is nice except during the Bb chord. (I picked up a guitar for this one, it's a nice guitar piece.)


Luckiest Man- Dm/F - which when written on the stave have the same key sig. one flat. However, he's playing with capo on fret 1.

Say it Ain't So - Eb, moving to relative minor of Cm.

Where is my Mind - E, and its relative minor, C#m.

All use the V of the relative minor, which is usually a major or 7th chord not found in the relative major's armoury.

A song in a major key often MODULATES to its relative minor, sometimes only for a bar or two, sometimes for a whole section. The key sig., however, will remain the same.

As far as is it G# or Ab - it usually goes with the key sig. As in a piece in E, with 4 sharps, it will be called G#, not Ab.In Eb, with 3 flats, the 'G#' must be Ab. On most instruments with equal temperament tuning, it's the same note, but technically needs to be called the right name.

  1. E C#m G# A: Answer, key of E. Sharps in E are F#, C#, G#, D#. A is a natural note in the key. To determine sharps in a key: The note before the Key which would be D# in key of E is the last sharp. The rest follow the circle of fifths clockwise (each a 5th apart): F# C# G# D# and you're at E.
  2. C#m, G#, A, E: This is the same, key of E, using the same sharps and natural notes as above.

3 Dm, A, A#, F This appears to be key of C. The chords in key of C are C Major, Dm, Em, F Major, G7, Am (more often played as an A7) and B diminished. The A# is not in the key and is an accidental.

  1. "Is it sharp or flat?" The sharps are explained above. The flats begin with the key of F which has one flat, b flat. Then following the Circle of Fifths (now the Circle of Fourths) to the left, the flats are (count in fourths) Bb Eb, Ab, Db, Gb, Cb. The key of F has one flat, Bb. The key of Bb also has Eb, a fourth higher on the Circle of Fourths. Eb has Bb, Eb, and Ab also a fourth higher. So it's easy to find what flat key your are playing in. I use the acronym BEAD GC to determine the flat key. The keys of the natural notes (except F) have no flats. The flat keys have no sharps. I hope this helps you. Gary

P.S. When you look at a chart of all the notes on a guitar, you'll see that the flats share location with a sharp. Bb and A#, Eb and D#, Ab and G#. This is because they are enharmonic, they sound alike, but they are not from the same keys.

Not the answer you're looking for? Browse other questions tagged or ask your own question.