The Easy Way to Understand Intervals on the Piano

With traditional piano study, it's difficult for an aspiring piano player to get excited about intervals. I remember experiencing a lack of motivation when I was a student. I believe it's because of not understanding what intervals are for. In this article, I want to share with you an easy way to understand intervals on the piano.

First of all what are intervals? An interval is simply the distance between two notes. It tells us how far apart notes are. This is easy to see on the piano keyboard because if you have two notes, there's an interval between them.

Intervals are defined by two different properties:

1 The quality of the interval.
2 The number (or value) of the interval.

We'll start with the number of the interval first because it actually defines the interval as a whole.

As you may know, notes have lettered names. You can find the number of the interval by simply counting how many notes are between them. Just be aware that sharps and flats do not apply when you're determining the numeric value of an interval. In other words, the same number can apply to two different notes even though they are not the same distances.

You should also be aware that intervals are counted from the bottom note to the upper note.

Here are some examples:

Here we have C and G. If we inclusively count the notes from C to G, we have 5. In this case, a 5th interval.If we have C and G flat and count up to five, we still have a 5th interval. (remember, we're not considering interval quality yet.)A to C sharp is a 3rd interval...

...and so is A to C.

Can you name the numeric value of these intervals? (Remember at this step, we're ignoring sharps and flats. Just count the letters)7th interval

4th interval

6th interval

One more...

8th interval

Once again, not all of these intervals that have the same number are the same distance from one another. We have to factor in the interval quality.

As you can see, it's pretty straightforward to determine the number of the interval. Beyond this, we have to define the quality of the interval. Interval quality can be labeled in one of five different ways:

1 Perfect
2 Major
2 Diminished
3 Augmented

A perfect interval is a fourth, fifth, octave or unison interval. So how do we determine a perfect interval? This is where knowing our Major keys of music comes in. Let's say we have the following 4th interval.We know that this is a fourth interval. But how do we determine if it's a perfect fourth? Since the bottom note is a C, we'll reference the key of C Major. All we need to determine is whether the upper note is in the same key as the lower note. This is also known as a diatonic note. (a note that is in the key).As you can see there is an F in the key of C Major so this verifies the C and F as a perfect 4th interval.

Let's take a look at a perfect 5th.

Since we have a D as the bottom note, that's the tonic of the key of D Major.

As you can see, A is a diatonic tone so D and A is perfect 5th interval.

A perfect octave interval is even simpler to determine.

You'll refer to the bottom note again as the tonic to determine the key of music to reference.Since B flat is an octave of B flat, it's confirmed to be a perfect octave.

The last perfect interval we'll look at is a perfect unison. Wait, how can a note have an interval with itself? Of course you can't play one note on the piano and harmonize it with the same note. But look at it this way, imagine having two pianos side by side and they're each playing the same note. This is an example of perfect unison.

By the way, some students ask: Why are these intervals referred to as "perfect"? Well, we could get into the science of sound and how the ratio of their frequencies are simple whole numbers, but the best way to think of perfect intervals is that they have a very consonant and agreeable sound. They sound "perfect" when played together.

A Major interval is a second, third, sixth, or seventh interval. Again, this where knowing our Major keys of music comes in. Let's take a look at a few of them using the same strategy of referring to the bottom note as the tonic of the key.So C Major is our key.Since D is a note in C Major, it's a Major 2nd.

Here's a 3rd interval in A Major. Is it a Major interval?Is C sharp in the key of A Major?Of course C sharp also exists in the key of A Major so it is a Major 3rd.

In this example we have B and G sharp. It's easy to determine that the interval value is a 6th.  Are you familiar enough with the key of B Major to know if it is a Major interval?We can see in our example that it is, so G sharp is a Major 6th.

So what about the Major 7th? I think you're getting the hang of it so take a look at this example.Here's the key of G Major. Is F sharp a Major 7th interval?We can see that F sharp exists in the key of G Major so it is the Major 7th.

Diminished and Augmented intervals have something in common with each other. That is, if any of the top notes are moved by a half step up or down, the quality of them will change to one of these categories. In case you're not familiar, a half step is the distance from one key to the very next without skipping a key.

Diminished intervals are often referred to as minor. Real world musicians will often refer to them differently in which I'll explain coming up.

Here's C and D flat. We know that C to D is a 2nd. All we need to determine is the quality of the interval.

In the key of C Major there is a D but no D flat.

Since it's a half step below the D, it's a diminished 2nd.

Here we have C and E flat.The key of C Major shows us that C Major doesn't have an E flat so it's technically a diminished 3rd interval.Just a quick note about diminished 3rds. They're actually referred to as minor 3rds. Most musicians reserve the term "diminished" for other intervals. If you know your Major and minor triads, you're aware that the only element that separates them is the Major and minor 3rd. So minor is always used instead of diminished in reference to 3rds.

Here we have D and A flat.We can see that this is a 5th interval before we determine the quality of it. Let's see if the key of D Major contains an A flat.As you can see, A flat is a half step below A which reveals that this is a diminished 5th interval. Contemporary musicians will often refer to this as a flat 5th interval.

Here's B flat and G flat.We can see that it's a 6th interval but let's look at the key of B flat to determine its quality.

G flat is half step below G so it's a diminished 6th interval.

Here's E and D.Now, look the key of E Major.Since D is a half step below the 7th, its a diminished interval. This is another interval that most musicians just refer to as a flat 7th instead of a diminished 7th.

Let's take a look at F and B.The number of this interval is clearly a 4th, let's look at the key of F Major to determine its quality.There's no B in the key of F Major, but since it's a half step up from B flat, we can be certain that it's an augmented 4th interval.

Let's take a look at one more interval.You should be aware by now this is a 5th interval. Is there a D sharp in the key of G?Seeing that its a half step above the perfect 5th shows it's an augmented 5th.