Intervals

Words to know: interval, half step, whole step, octave, scale, frequency, accidentals

By now, hopefully you’ve seen the lesson on half steps and whole steps. If not, make sure you’re familiar with them first. Everything I talk about in this lesson is based off of the idea of half steps, so if you’ve missed that one you might be a little lost. You may also want to check out some of my Music Theory Basics lessons to learn more.

What is an Interval?

An interval in music refers to the space between two notes. The space, as you might imagine, can be quite small or quite large. It all depends on the number of half steps between the two notes you are looking at. Each interval has a different name that notates its size, and since we’re dealing with music and not simply distances, each interval has its own distinct sound.

We all hear intervals every day, though we never think of it. The siren of an ambulance, television slogans, cell phone ringtones, even our voices; these all contain intervals. Every song on the radio is made up of dozens of intervals that act together to create tunes that we remember. The more pleasing the intervals sound, the more pleasing the song as a whole sounds.

In Western music, we have 12 basic intervals. I’ll break them into three groups for the purpose of this lesson: major intervals, minor intervals, and odd intervals. These are not official musical names for them, but it may help you to understand what I’m talking about. As always with these theory lessons, I’ll use the piano keyboard as the basis for my visual aid. Let’s talk about major intervals first.

Major Intervals

A major interval refers to the distance between the first note in a scale and another note in that 8-note scale. For more information on scales, see my scale lesson. In my last lesson, Whole and Half Steps, I mentioned black keys and white keys as we would find on the piano. (If you’re not familiar with the piano, I have a short tutorial here). For this example, we’ll use the C scale because it uses all white keys with no black keys (starting on C and going up or down the keyboard to the next C using consecutive white keys only). We will assign each white key a number, 1-8, to correspond with the 8 notes of the C scale. We call these numbers “Scale Degrees.” These same numbers and interval relationships can be used on any scale, but remember all other major scales will make use of some black keys whereas the C scale only uses white keys.

The following chart shows the interval relationship between each note of the C scale, the scale degree assigned to each (with the low C being “1” and the top C being “8”), as well as how many half steps make up the interval.

Pitch Intervals	Scale Degrees	# of Half Steps
C-D	1-2	2
C-E	1-3	4
C-F*	1-4	5
C-G*	1-5	7
C-A	1-6	9
C-B	1-7	11
C-C*	1-8	12

This may look confusing, but really it’s three different ways of looking at the same thing: the distance between two notes. The first part of the chart shows the letter names of the notes we’re measuring between, such as C-D. The second part shows what their designated scale degree is. In this case, since it is a C scale, C is given a one and D, which comes after C, is given a two, etc. The third part shows how many half steps are between the two given notes. This becomes particularly important when looking at scales.

In music, instead of keeping the two numbers to designate which notes of the scales we are measuring between, we often just use the second number to name the interval. Thus, instead of writing the distance between C and E as being the first note to the third note (1-3), we would call it a “3rd”. And since it is on the white keys, we call it more specifically a “major 3rd”. So, the whole chart is more accurately shown as:

Pitch Intervals	Interval Name	# of Half Steps
C-D	Major 2nd	2
C-E	Major 3rd	4
C-F	Perfect 4th*	5
C-G	Perfect 5th*	7
C-A	Major 6th	9
C-B	Major 7th	11
C-C	Octave	12

You may notice that, with two exceptions, there is a two half step difference between consecutive intervals. This is because of the way scales are made, which I’ll talk about in my Scale lesson. Also, the numbers of half steps that are not in this 8-note sequence are listed below. Take a look at a piano as a visual reminder of the note locations.

Minor Intervals

Minor intervals are the measurement of the distance between the starting note of a scale and the “accidentals”, or notes that are not in the 8-note major scale. In the C scale, all of these accidentals will fall on a black key, since the major scale only uses white keys. Remember, since the black keys are between the white keys, they all have two names depending on which way you come from; either a flat if you move from above the note down the scale, or a sharp if you move from below the note up the scale. For the purpose of this lesson, I’ll name them by their “flat” names just to keep it all consistent.

Since the major intervals above are labeled as “2nd, 3rd,” etc., the minor intervals are labeled the same way. However, because there is one less half step for each one, we call it a “minor 2nd”, “minor 3rd”, and so on. I’ll leave the “fourth” and “fifth” out of this list, because they are a little different. They’ll be in the “Odd Intervals” section below.

This chart, similar to the one above, shows the relationship between the starting note, C, and each of the black keys in order from left to right on the piano keyboard.

Pitch Intervals	Interval Name	# of Half Steps
C-Db (D flat)	Minor 2nd	1
C-Eb (E flat)	Minor 3rd	3
C-Ab (A flat)	Minor 6th	8
C-Bb (B flat)	Minor 7th	10

Odd Intervals

There are five intervals in every scale that don’t quite fit in with all the rest. These are:

Pitch Intervals	Interval Name	# of Half Steps
C-C (same note)	Unison	0
C-F	Perfect 4th	5
C-F#	Tritone	6
C-G	Perfect 5th	7
C-C (next C)	Perfect Octave	12

All you need to know for now is that these intervals, with the exception of the tri-tone, are considered to be perfectly in tune and are labeled as “perfect”. If you want a more detailed explanation, read on. But I’ll warn you: it gets a little awesome.

The four “perfect” intervals are labeled like that because of the physics of sound. Sounds are basically just vibrations in the air that our ears pick up, and each sound vibrates as a specific speed, which we all the “frequency”. Of course, a unison note is the same note and so is tuned perfectly the same. An octave, which is 8 notes above or below the first note, is called perfect because the pitch vibrates at either 2x (higher octave) or .5x (lower octave) the original frequency and is considered exactly in tune with the original, just higher or lower pitched.

The perfect 4th and perfect 5th are also named for their pure frequencies. This can be demonstrated by plucking a string that is being held at either end. The string will vibrate at a certain speed, or frequency. If you hold exactly the center of the string and pluck one side, that frequency will be cut in half, producing a “perfect octave” above the original note. If you hold that smaller string exactly in the middle and pluck one side, it will produce a perfect 5th from that new octave note, which is considered to be mathematically perfectly in tune. If you hold that smaller string in the center again and pluck one side, that pitch would be a perfect 4th from the previous note. The interval would continue getting smaller but only the “perfect” intervals of Unison, 4th, 5th, and Octave are said to be perfectly in tune.

The tri-tone is a little different. It is sometimes referred to as a flat 5 or a sharp 4 (in a C scale, it would be a G flat/F sharp). It is called the tri-tone because it is exactly halfway between the first and last note of the scale, counting all the black keys in between. This makes three points of reference: the first note, the tri-tone, and the last note of the octave. Unlike the perfect intervals above, this note is not considered to be exactly in tune. However, because a lot of people think it is very uncomfortable to hear, it was formerly called the “Devil’s Interval”. A great example of a tri-tone can be heard in the first two notes of the song “Maria” from West Side Story.

Recap

If you’ve stuck with this page long enough to get here, you realize that there’s a ton of information here. The best way to learn it is to use it. Write some short tunes, read more about it, watch videos.

This is the complete chart of the intervals and the number of half steps in each. They can be applied to any scale, not just to C scale we used earlier, so I’ll leave out the letter names here. I’ll also give you some songs to help you recognize each interval by sound. Each song example will be the first two notes of the song.

Interval Name	# of Half Steps	Sounds Like
Unison	0	“Peter Gunn” theme
Minor 2nd	1	“Jaws” theme
Major 2nd	2	“Happy Birthday”
Minor 3rd	3	“Greensleeves”
Major 3rd	4	“Sweet Hour of Prayer”
Perfect 4th	5	“Here Comes The Bride”
Tritone	6	“Maria” (West Side Story)
Perfect 5th	7	“Twinkle Twinkle Little Star”
Minor 6th	8	“Love Story” (backwards)
Major 6th	9	“NBC” Theme
Minor 7th	10	“A Place For Us” (West Side Story)
Major 7th	11	Theme from “Fantasy Island”
Octave	12	“Somewhere Over the Rainbow”

Thanks for reading! If there’s anything you’d like me to talk about, leave a comment or email me and let me know. Share this page with your musical friends, and let’s learn together!