Most western music is composed with only 12 notes. There are 7 “natural notes” (the white keys on the piano, A to G) and 5 sharp notes (the black keys, C#, D#, F#, G#, A#, we’ll cover the flats another time). Notice that there are no sharps between B and C, and also E and F. If you refer to the keyboard, you’ll see that there are no black keys between those notes, so instead of going from B to B#, you’ll go from B to C. With that understanding, we can now discuss intervals!
An interval is the distance between any two notes. There are 12 intervals, each with a different name correlating to how many semitones there are between the two notes.
A semi-tone can be defined as the smallest possible interval that we can play with. It is also sometimes called a half-step. So, the distance from one note to the next possible note on a keyboard (e.g. going from B to C, or from F# to G) would be a semi-tone.
On a guitar, moving up a semi-tone is the equivalent of moving up one fret (e.g. from frets 5 to 6, or 2 to 1). Moving forward, we will measure all intervals using semi-tones.
. Now I will lay out the names of each of the 12 intervals and how to measure them using semi-tones.
- m2 (minor 2nd) – this is a single semi-tone
- M2 (Major 2nd/whole-step) - 2 semi-tones
- m3 (minor 3rd) – 3 semi-tones
- M3 (major 3rd) – 4 semi-tones
- P4 (Perfect 4th) – 5 semi-tones
- A4/D5 (Augmented 4th/Diminished 5th/tri-tone) – 6 semi-tones
- P5 (Perfect 5th) – 7 semi-tones
- m6 (minor 6th) – 8 semi-tones
- M6 (major 6th) – 9 semi-tones
- m7 (minor 7th) - 10 semi-tones
- M7 (Major 7th) – 11 semi-tones
- Octave - 12 semi-tones
*an octave is where you play the same note 12 semi-tones apart (the same as 12 frets on the guitar). For example, if you played a C on the piano, and also played the next possible C on the piano simultaneously, you’d have an Octave.
Every melody you’ve ever hummed is a sequence of intervals played one after the other. Have you ever heard of a little tune called “Twinkle Twinkle Little Star”? Cheesy, I know, but everyone knows it. If you were to play this sequence of notes on a keyboard (pull out your phone if you’ve got a keyboard app!), you would get that sweet little jingle we all know and love to hate: C, C, G, G, A, A, G, F, F, E, E, D, D, C. Did you play along? Nicely done!
Now I’ve got a little test for you. Can you figure out what intervals are being used in twinkle twinkle little star? (Answers below)
Example: A to G = a whole-step, or a M2 (Major second)
- C to G =
- G to F =
- F to E =
Answers: 1. P5 (Perfect 5th) 2. M2 (Major Second/whole-step) 3. m2 (minor second/semi-tone)
Now let’s get a little spicier and talk about Chords. Chords are just intervals stacked on-top of each other. Every single chord has a formula that can be constructed using intervals.
Let’s take a look at the formula for a Major Chord, and let’s do it starting with the C note.
Every major chord uses the following formula: 1, M3, P5 (or just 1 3 5)
If we were to apply this formula to the C note (C being the 1 in the formula) you’d get a C Major Chord: C E G.
Let’s take a closer look at what’s going on here. If you played a C on your keyboard, and then counted 4 semi-tones up the piano (a Major 3rd), you’d land on the note E. That makes E the
Major 3rd (the 3 in the formula). If you counted 3 semi-tones from E, you’d arrive at G, which is the 5 in the formula. That’s one way to find the 5 in the major chord formula, but you could als just count 7 semitones or a P5 (Perfect 5th) from C to G. Do you see how each of these intervals relates to each note’s place in the Major Chord formula?
Let’s build another Major Chord Starting on F. If you count 4 semi-tones (a Major 3rd) from F, you’d land on the note A. Count another 3 semi-tones from A and you arrive at the 5 in the formula, C. You could also count 7 semi-tones (a Perfect 5th) from F to find the 5 of the chord, C. By applying the Major Chord formula to the note F, we’ve built an F Major Chord:
F A C
You should now be able to construct a Major Chord starting from any note by using this formula. Let’s try it!
Build a Major Chord starting from the given note (answers below):
- D Major = D F# A
- A Major = A C# E
- G Major = G B D
- E Major = E G# B
If you’ve made it this far, give yourself a flippin’ pat on the back. Music Theory can be a daunting subject, but it also enriches just about every musical experience you’ll have. Thank you for sticking with me!
If you’d like to learn to do the same for a Minor Chord, the formula is very similar! Starting from the note D, instead of counting 4 semitones (a Major Third) from D, you’d count 3 semi-tones (a minor third) from D which brings you to the note F. If you count 4 semi-tones from F to A you get the 5 of the D minor chord. Notice how the minor chord formula has the same two intervals stacked on top of each other, but in the minor chord formula you start with the minor 3rd (3 semi-tones) instead of a major 3rd (4 semitones). The 5 in the chord formula doesn’t change between Major and Minor. So, how would you play a D minor Chord?
D F A
1, m3, P5
Can you spot the difference between the D Major Chord in the “Answers” section above and the D minor Chord? You guessed it! The F# in the D Major Chord was lowered by 1 semi-tone to the note F, thus transforming the chord from D Major to D minor! If you’ve got access to an instrument , try playing a D Major Chord and then lowering the 3 from F# to F, so you get a D minor Chord. Your ear will certainly notice the difference!