Music intervals: count the number, then find the quality

An interval describes the distance between two pitches. Names such as “major third” and “perfect fifth” combine a number with a quality. The number comes from the written letter positions; the quality makes that distance more specific. Counting piano keys alone does not tell you the complete written interval name. Source: Music Theory for the 21st-Century Classroom, intervals.

For this guide, use ascending intervals within an octave, with the first named pitch lower than the second. Write the actual note spellings, including sharps or flats. We are naming written intervals; identifying them reliably by ear is a separate listening task.

Keep two spaces on your worksheet: “number” and “quality”. Filling them separately helps reveal whether a mistake came from counting letters or comparing pitch distances.

For E to G, count E as 1, F as 2 and G as 3: it is some kind of third. E to G-sharp is also a third because the letters are still E–F–G. Accidentals affect the quality, not this letter count. For D to A, count D, E, F, G, A: five letters, so some kind of fifth. Source: Open Music Theory, interval size.

This differs from counting semitone moves, where the starting key is zero distance travelled. Say “letters include the starting note; moves begin after it” while you work. Mixing those two counting procedures is an easy way to produce a correct-looking answer with the wrong number.

Do not remove the accidental from the actual pitch when you move to the second step. Temporarily ignoring it helps count letters; permanently ignoring it loses information you need for quality.

From a major scale’s tonic, degrees 2, 3, 6 and 7 form major intervals; degrees 1, 4, 5 and 8 form perfect intervals. For a simple ascending example, build the major scale on the lower note and compare the upper note with the matching degree. Source: Music Theory for the 21st-Century Classroom, identifying intervals.

Take E to G-sharp. Its number is three. E major begins E, F-sharp, G-sharp, so the given upper note matches the scale’s third: a major third. E to G-natural has the same number but is one semitone smaller: a minor third.

For the perfect family, “minor fourth” is not the corresponding standard label. Making a perfect fourth one semitone smaller gives a diminished fourth; making it one larger gives an augmented fourth. In the major family, one semitone below minor is diminished, while one above major is augmented. Source: Open Music Theory, interval qualities.

Use the reference interval first rather than memorising a rule that every flat means “minor”. A flat can appear in a major interval, and a sharp can appear in a minor one; the relationship between both notes determines the answer.

Compare C to F-sharp with C to G-flat. Each spans six semitone moves on the piano, but C–D–E–F counts four letters, while C–D–E–F–G counts five. C to F-sharp is an augmented fourth; C to G-flat is a diminished fifth. Their piano sound can coincide while their written interval names differ. Source: Open Music Theory, enharmonic intervals.

Write the number before looking at the keyboard distance. If your answer is “six semitones”, you have supplied useful checking information but have not yet identified the spelled interval. This is why a chart of semitone totals needs letter context.

For each ascending pair, record the number, a major-scale reference and the final quality. Keep the notes within one octave.

1. G to B-flat
2. D to A
3. F to B-natural
4. A to C-sharp

Check the worked answers

1. Minor third: G–A–B gives three; G major has B-natural, and B-flat is one semitone lower.
2. Perfect fifth: D–E–F–G–A gives five; A is the fifth degree of D major.
3. Augmented fourth: F–G–A–B gives four; F major’s fourth is B-flat, so B-natural is one semitone higher.
4. Major third: A–B–C gives three; A major has C-sharp at its third degree.

As a final check, try C-sharp to E. C–D–E still gives a third. C-sharp major’s third is E-sharp, so E-natural is a semitone smaller: a minor third. The sharp on the lower note does not automatically make the interval augmented.

If the reference scale is the difficult part, revisit constructing major scales before attempting a long interval quiz. If the number is wrong, practise letter counting without accidentals first, then restore them. Add one explained example to your practice record. For assessment preparation, check which interval tasks your chosen exam route actually requires.