Interval Names: Prime, Second, Third, Fourth, Fifth, Sixth, Seventh and Octave

In the last blog post I explained the logical system behind note names. A similar system exists for tone distances also called intervals. Lets talk about this.

What is an interval?

The distance between two tones is called an interval. The orange arrow in the following figure illustrates an interval on the Animoog keyboard.


Why intervals are so important?

When we’re composing a melody, the absolute pitches are less important. The tonal character of the piece will depend much more on the distances of neighbouring tones. The melodies c-d-e-d-c and a-b-c#-b-a for example consist of different tones but they sound quite similar. The reason is, that the intervals of the pieces are the same in both sequences. With interval names we can characterize a musical piece much better than with absolute note names.

Estimation of interval names

Intervals got the names prime, second, third, fourth, fifth, sixth, seventh, octave and so on. These names are derived from the diatonic scale, e.g. the c-major scale. Let’s use the example c-a to explain this.


To get the name of that interval we need to count the scale tones from tone c to tone a. That means in the case of a c-major scale we must only count tones belonging to the c-major scale.


Tone a has got the number six which is some kind of measure for the distance c-a. Thus the interval c-a is called “sixth“.

The first eight interval names

In the same way also the other intervals can be derived. The interval names are straight forward. Exceptions are the first and the eight interval which are called prime and octave.

Scale step range Interval Name
1 Prime
2 Second
3 Third
4 Fourth
5 Fifth
6 Sixth
7 Seventh
8 Octave

Practicing interval names with Animoog

It is important to know how different intervals sound. The best way to learn this is to play intervals at a musical instrument while singing the interval’s name. How this can be done with the synth app Animoog is part of the following video.

Next episode

The eight interval names prime, second to octave are not precise enough. Thus the names do not distinguish between the second c-d and the second e-f for example. Therefore the next episode will be about major and minor intervals.


  • Intervals play an important role for the perception of melodies and chords.
  • To estimate an interval roughly we simply need to count the scale-steps from the first interval tone to the second. 
  • The name of the interval directly corresponds to the number of scale steps. Exceptions are the prime (1) and the octave (8).

10 thoughts on “Interval Names: Prime, Second, Third, Fourth, Fifth, Sixth, Seventh and Octave”

  1. It’s a little confusing, though, that in the harmonic series, the third harmonic is corresponds to “a fifth” and the fifth harmonic corresponds to “a third”. There, I’ve confused you!
    You can find a diatonic major scale hiding in the 24th to 48th harmonic intervals, and many other scales as well.

    1. Yes, I’m also not happy that scale distances are used for interval names. Thus the names tell nothing about the perceived quality. A relation to harmonics or to interval ratios would be much better.

      1. It does end up being an advanced can-o-worms because chromatic scales don’t exactly line up with any pitch ratios beyond the octave. Though.. circle of perfect fifths (the physical justification for pentatonic, diatonic, and chromatic shapes), and circle of maj thirds (whole tone shapes), circle of min thirds (harmonic minor shapes) are an interesting thing to go over if you ignore the intonation details.

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  2. Nice, clear explanation. I would add that people often use the first interval of familiar songs to remember the sound of each interval. It works very well. For example, “May all,” the first words of Auld Lang Syne is perfect 4th. (If sung, of course!) The list on the site below is good because it includes several songs for each interval in hopes that you are familiar with at least one. I don’t know how much this system is used in languages other than English.
    Also, to avoid confusion, be aware that intervals go both up and down, and this list includes and identifies both.

      1. I figured you’d get to it. Just thought it could be helpful to those who are going to jump in immediately. I would be interested to know if there is a different set of songs in German used for the same purpose. Must be, right?

  3. I’m interested to see what you’re going to go from here… I’ll be especially interested to see how you tackle major and minor intervals next time. So far, it’s all been review for me (which is a good thing!). I see someone else already mentioned perfect fourths and fifths, so I’ll just be repeating what he said. Good series so far!

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