Sizing Up Intervals to Play the Harmonica

By Winslow Yerxa

Very few people have the ability to name what note they’re hearing. That ability is called absolute pitch or perfect pitch. But most harmonica players and musicians have a much more useful skill: They can hear and describe the relationships among notes using intervals. Those relationships create structure in scales, melodies, chords, and harmonies. When you know the structures, the specific notes are just details that you can figure out.

Counting out the size of an interval

An interval is the distance between two pitches. You measure the size of an interval by starting with the letter name of the first pitch and then counting up or down the scale to the second pitch. You already know two intervals — the unison, where two people sing the same note, and the octave, where they sing two pitches that are eight notes apart in the scale.

You can memorize all the intervals, but it’s easy to figure out any interval just by counting:

  • Choose one of the notes and give it the number 1.

  • Count up or down to the other note. The resulting number gives you the interval.

    • Seconds: Counting up from A to B (1, 2) gives you a second. So does B to C, C to D, and so on.

    • Thirds: Count up 1, 2, 3.

    • Fourths: Count up 1, 2, 3, 4.

    • Fifths: Count up 1, 2, 3, 4, 5.

    • Sixths: Count up 1, 2, 3, 4, 5, 6.

    • Sevenths: Count up 1, 2, 3, 4, 5, 6, 7.

  • If you’re starting with a specific note name and want to know what note would be, say, a fifth above it, just start on the note name you know, count up 5, and you’ll arrive at the other note name.

Here are all the intervals up to an octave counting up from any note name.

1 2nd 3rd 4th 5th 6th 7th Octave
A B C D E F G A
B C D E F G A B
C D E F G A B C
D E F G A B C D
E F G A B C D E
F G A B C D E F
G A B C D E F G

When you’re figuring out the size of an interval, only letter names matter. Sharps and flats have no effect. However, flats and sharps do affect the quality of intervals.

Determining the quality of an interval

While every interval has a size counted in letter names, it also has a quality measured in semitones. For instance, the second between C and D is a whole tone. However, the second between E and F is only a semitone. So one of those seconds is bigger and one is smaller. The bigger second is called a major second and the smaller second is called a minor second.

All intervals have at least two qualities, even the octave. Here are the most widely used qualities of intervals.

Interval Size Interval Quality Number of Semitones
Second Minor 1
Second Major 2
Third Minor 3
Third Major 4
Fourth Perfect 5
Fourth Augmented 6
Fifth Diminished 6
Fifth Perfect 7
Fifth Augmented 8
Sixth Minor 8
Sixth Major 9
Seventh Minor 10
Seventh Major 11
Octave Perfect 12