Major and Minor Intervals

Interval Interval Number Semitone and Whole Tone Perfect Intervals Triad Scale

Major and minor are not adjectives but a two-way split: at the same degree, the wider version is called major, and the one a semitone narrower is minor. C–E spans four semitones and is a major third; C–E♭ spans three and is a minor third. One letter of the name changes, and the sound almost inverts — which is why this split deserves its own entry.

Which degrees split

Not all of them do, and the rule is tidy:

Degree	Splits?	The two members
second	yes	major second (2 semitones) · minor second (1)
third	yes	major third (4) · minor third (3)
sixth	yes	major sixth (9) · minor sixth (8)
seventh	yes	major seventh (11) · minor seventh (10)
unison / fourth / fifth / octave	no	perfect only — see [[concept:perfect-interval

Those four groups are exactly the four variable positions in a scale. The only difference between a major and a minor scale is that three of them (third, sixth, seventh) switch from major to minor.

One semitone apart, yet worlds apart

Because of a three-way division. An octave splits into three stretches: tonic to third, third to fifth, fifth to octave. Which side the third falls on decides the whole triad's light or shade:

major third + minor third = a major triad (bright, stable)
minor third + major third = a minor triad (dark, inward)

Both triads use the same three letter names. The only difference is which stretch that one semitone falls into. This leads straight to triads, and it is the switch behind every key change from major to minor in popular music.

Diagram: major and minor, one semitone apart

Listen: major third against minor third

One semitone apart: one is bright, the other dark. This pair is the master switch of harmonic colour.

Common misconceptions

"Major means louder." Unrelated. Here it means one semitone wider; loudness plays no part.
"Every interval comes in major and minor." Unisons, fourths, fifths and octaves are perfect only. Their wider and narrower forms are augmented and diminished.
"A minor third is lower." Both start on the same note; only the endpoint drops a semitone. The major third sounds wider, not higher.
"Major and minor differ by the key signature." The real difference is whether the third, sixth and seventh use the major or the minor form. The key signature is a consequence.

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Listen in the library

27. Greensleeves to a Ground with DivisionC10:24The rising leap that opens Greensleeves is a minor third — the most quoted example on the minor sideDetailsScales, Arpeggios, and CadencesC13:22Arpeggio exercises spell out major and minor triads, placing major and minor thirds side by sideDetailsAmazing GraceC11:09The perfect fourth that opens Amazing Grace is the control case — it belongs to the perfect family and takes no major or minorDetails

All tracks from midicn-lib — inline badge is the license tier (C1 commercial / C2 non-commercial / C3 study only).

Sources

大/小音程定义为"同度数下音数相差一个半音"，属乐理通则
大小音程只出现在二、三、六、七度，一、四、五、八度为纯音程，为通行表述

Used for fact-checking only; all prose is original.

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