• Josh Warriner

Music Theory or: The Mathematical Method of Music-Making

If you’re a musician, or an aspiring musician, you might have wondered about music theory. Perhaps it has you perplexed, or perhaps you know a little and don’t know what extent you show learn. You might have wondered whether or not it’s something you need as a musician. We've outlined below just how theory is essential to musicianship (and how much you should know.)

Is Music Theory Essential?

Music theory gets a bad rep. It is the foundation upon which music is built. It is the mathematical steps you need to take your music to its greater creative potential. Fundamentally, music theory is math. But not the scary, “will this be on the exam?” sort of math. This is the C major = A minor sort of math. When presented all at once music theory can seem daunting, even scary, but in reality it is far from it.

In the spirit of making music theory as worry-free as it can be, we’ll break down a few of its key components below, and tell you where you can learn more about theory's in-depth components.

The Key Terms

The Key Signature

There are 24 tonally unique key signatures in western music. This means that number does not include keys which are sonically identical (such as F# and G♭.) A key signature is important as it is the foundation for what notes you can find in the key you are writing in, particularly in regard to sharps and flats.

However, how are you supposed to know what key has how many sharps or how many flats respectively? There's a little illustration you should probably know:

The Circle of Fifths


Don't let this image frighten you if you don't know it well. Let's break it down.

The basis of the circle is simple, it tells you all of your available key signatures, and how many sharps or flats can be found in them. If you follow the circle starting at the first flat going clockwise, you get the acronym for knowing which notes those sharps or flats are. FCGDAEB, or as I was taught it if you need an association: Father Charles goes down and ends battle. This is the system for the major keys. The minor keys are a bit different but we'll get to those shortly.

So let's take an example. We'll start with something simple, G major:

As we can see, Gmaj has one sharp. Using our acronym, we know that this sharp is F#. Thus the notes we have available in Gmaj are as follows: G, A, B, C, D, E, F#.

One more example, let's take something a little harder, E♭major:

Using the circle, we can see that E♭maj has three total flats. When it comes to keys with flats rather than sharps, we simply use our acronym backwards, BEADGCF. Thus with three flats, we know the notes available to us are. E♭, F, G, A♭, B♭, C, D.


Finding these notes for a key signature also tells us what chords we can use in a song in that key. There are seven chords per key, and in a major key, this must be remembered: I, ii, iii, IV, V, vi, viiº. This tells you what chords are major and minor (with vii being a diminished chord.)

Thus in G major we know we have the following chords: Gmaj, Amin, Bmin, Cmaj, Dmaj, Emin, F#dim.

Chord Progressions

Every western piece of music is based on chord progressions. Within a key, the order which you choose to arrange your chords is important to your song. There are some chords that naturally sound good together. For example, the V of a key always wants to pull to I. So an example of a typical progression of Gmaj would be: Gmaj, Cmaj, Dmaj. Very pop-friendly.

On Minor Keys

Every major key has a friend, its relative minor, as you can see on the circle we discussed earlier. These relative keys share the same key signature as their major counterparts, but simply start on their respective note. The chords in a minor key are as follows: i, iiº, III, iv, v, VI, VII.

Thus in G major's relative E minor we have: Emin, F#dim, Gmaj, Amin, Bmin, Cmaj, Dmaj. Notice a pattern? The same chords! This just changes the relationship between them.


This is an overview of the basic level of theory to get you started, hopefully it helped you out! If you want to learn more, there's a lot of fantastic music theory websites out there that get down to the finest detail if you want an absolute mastery of it, such as https://www.musictheory.net/ and https://www.basicmusictheory.com/.

Stay tuned this week from some exciting announcements from the Populus Music network!

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