Understanding Intervals: The Key To Music Theory

Weekly Newsletter #15

November 18, 2021

For this week’s newsletter, I wanted to shift gears from technique and discuss one of the most fundamental concepts of music theory: Intervals. 

If you find yourself intimidated by music theory and unable to begin the journey of understanding it, this will be the ideal way to get started. 

For those who are looking to find new ways of playing chords or who want to understand how to build your own chord shapes, this will be very useful for you. 

To begin, it is important to understand what an interval is and how to make sense of them. 

Essentially, an interval is merely the distance between two notes. When I say distance, you can think of the distance in terms of half-steps or whole-steps. Half steps are equivalent to 1 fret on the guitar, or 1 key on a piano. 

For example, if you move from the 5th fret to the 6th fret along one string on the guitar, you have moved a half-step. If instead, you go from the 5th fret to the 7th fret, you have moved a whole step. Simple right? 

The smallest interval possible is a half-step. Whether on piano, guitar or any other instrument within Western music, half-steps are the smallest distance between two notes. After all, there is no note between C and C#. 

Intervals have names and for our current purposes we will be limiting the intervals to within one octave, although, since they are just distances between two notes, they can theoretically be infinitely large. 

The names of the intervals within one octave are as follows: 

m = Minor                  M = Major                  P = Perfect                 TT = Tri Tone 


m2 - ½ step 

M2 - 1 step 

m3 - 1 ½ steps 

M3 - 2 steps 

P4 - 2 ½ steps 

TT - 3 steps 

P5 - 3 ½ steps 

m6 - 4 steps 

M6 - 4 ½ steps 

M7 - 5 steps 
m7 - 5 ½ steps 

P8 - 6 steps 


Ok, so I’m sure that looks very confusing, but let me break it down for you. 

The lower case “m” stands for minor and the upper case “M” stands for major. These aren’t chords, these are names of the intervals. If you notice, each minor interval is a half-step smaller than its partner the major interval. 

Take a look at m2 and M2. 

m2 is called a “minor second” and is one half-step. M2 is called a “major second” and is one whole-step. This means that if we started on the note C, an m2 would give us C# and an M2 would give us the note D. Remember a half-step is equal to one fret and a whole-step is equal to two frets. 

The same goes for all the other minor and major intervals. 


The Perfect intervals are very interesting and quite important. Perfect intervals are called “perfect” for two reasons. 

-Regardless of whether you are in a major key or minor key with the same root note (A major or A minor for example), the Perfect intervals will be the same note. 

-The Perfect intervals are the least dissonant intervals. These intervals’ wave forms line up either exactly or nearly exactly when both notes are played together. 

Take the interval of a Perfect 5th (P5) in the context of A minor. Play an A minor chord and take a look at the high E string. Its part of the chord right? Now play an A major chord. That high E string is also present in that chord as well. Now count the distance from A to E using the frets on your guitar. Start at any A note (the open A string will work) and count fret by fret until you get to the note E. If you’re counting on the 5th string you should have gotten to E on the 7th fret. This means that there are 7 half-steps or 3 ½ whole-steps from A to E. 

Now remember that the Perfect interval is the same whether you are in A major or A minor. This means that the 5th note of the A minor scale is E and the 5th note of the A major scale is also E…hence the name Perfect interval. 


Tri Tone only appears once but is a very interesting interval. It is one of the most dissonant intervals. So much so that it was actually outlawed for many years in European court music because it was said to have conjured up the devil. 

Now, if you count along your guitar from the open E string up one fret at a time you will be counting up the intervals. When you end at P8 you will be on E at the 12th fret. P8 stands for “Perfect 8” or the octave. 


So, the question is, how is this useful to you? 

Well, I am going to simplify chord construction for you right now using intervals. 

We will take simple three note major and minor chords for this bit. 


There is a “recipe” to making a major chord and a different one for making a minor chord. 

Major Chord: M3 + m3 

-Starting from the root note, go up a M3 (2 steps). This is the second note of your chord. From the second note count up a m3 (1 ½ steps). This will be your third note. 

-Alternately you can also go up a M3 from the root note then go back down to the root and count up a P5 for the third note. 

For example, if you start on C and go up a M3 you end up with the note E. From there count up a m3 and you get the note G. 

The notes of a C major chord are : C - E - G 

Notice that G is the P5 of C 


Minor Chord: m3 + M3 

-The inverse is true for the minor chords. From the root note count up a m3 (1 ½ steps), this will be your second note. From the second note count up a M3 (2 steps) and this will be your third note. 

For example, start on C and go up a m3; you end up with an Eb note. From there count up a M3 and you get a G note. 

The notes of a C minor chord are: C - Eb - G 

Notice how in both the C major and C minor chords the P5 is a G? This is why it’s called a Perfect interval. 


There is one final bonus chord for which you should know the recipe. The Diminished chord. 

Diminished Chord: m3 + m3 

-The Diminished chord is simply an m3 above the root note and then another m3 above the second note. 

For example: From C go up a m3 and you end up on Eb. From there go up another m3 and you end up on Gb. 

The notes of a C diminished chord are: C - Eb - Gb 

Now for a small “Aha” moment. Count the interval from C to Gb. You should have ended up with 3 whole-steps, or a TT (Tri Tone). 

Play a C dim chord and listen to how dissonant it is. It is because it has a TT instead of a P5. 

These three chords: Major, Minor and Diminished are all the chords within any key. If you can understand and utilize the three recipes for these chords than essentially you can play every chord in every key. 

There are many more uses for the concepts of intervals and we will build upon them in subsequent newsletters, but for now you should practice building chords using these three recipes. 

You can also refer to this previous newsletter for more info on these three chord types within a key. 

As always, if you have any questions or are confused by anything in the newsletter please contact me and I’ll be happy to help you out. 

Thanks for reading. 

Max Rich 

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