Minor second
The minor second spans one semitone with a just ratio of 16:15, the narrowest step used in Western tonal music.
From C
- Size
- 1 semitones
- Abbreviation
- m2
- Just ratio
- 16:15 (111.73 cents)
- Equal-tempered
- 100 cents (−11.73 from just)
- Inversion
- Major seventh
What it sounds like
The minor second is a dissonance and the narrowest step in common use. Its ratio, 16:15, is complex enough that the two notes rub against each other, and the beating is audible when they sound together. Melodically it is a small, tense step that leans toward its target. Harmonically it sounds harsh, so composers use it for colour and friction rather than rest. In the major scale it falls between degrees 3 and 4, and between 7 and 8.
How to recognise it by ear
A minor second sounds like the closest neighbour: the two notes sit almost on top of each other and rub. The reference is the opening of 'Für Elise', which descends from E to D♯ by a minor second. Listen for the rub and the pull, a tense step that wants to close. Any half-step move, such as E to F or B to C in C major, has the same character. Practice: play a minor second and a major second from the same tonic, back to back, until the difference in rub is immediate.
Theory
The minor second inverts to the major seventh, and the two together fill the octave, 1 plus 11 semitones. Quality changes from minor to major. Triads and common seventh chords are built from thirds, so the minor second appears mainly in passing tones and in clashes between a melody note and a chord. Its just ratio is 16:15, which measures 111.73 cents. The equal-tempered minor second is 100 cents, so the just size is 11.73 cents wider.
The minor second above every note
Spelled by letter name, so the interval’s number is always right: a minor second above E♭ is not the same spelling as above D♯.
| From | To | Hear it |
|---|---|---|
On the piano
Further reading
- Reading Intervals at Sight: Generic and SpecificFundamentals · 6 min
- Ear Training for Intervals: A Method You Can Practise DailyEar Training & Practice · 7 min
Questions
Is a minor second the same as a semitone?
A semitone is a size, and a minor second is a named interval. C to D♭ and C to C♯ both span one semitone, but C to D♭ is a minor second and C to C♯ is an augmented unison. The spelling tells a reader how the notes function, even when the keys are adjacent.
Why does a minor second feel tenser than a major second?
Both are steps, but the minor second packs the two notes into the narrowest space the scale allows. Its just ratio, 16:15, is more complex than the major second's 9:8, so the partials of the two notes clash more strongly. The major second opens the sound and reads as motion rather than strain.
Where do minor seconds appear in ordinary tonal music?
In the major scale they fall between degrees 3 and 4, and between 7 and 8. The leading tone resolves up to the tonic by a minor second. They also appear as passing tones and as suspensions, where tension is prepared and then released by a step to a consonant interval.