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Tomus

Interval reference

Minor second

2 letter names · 1 semitone · C → D♭

A minor second spans 2 letter names and 1 semitone. Both halves of that description matter: the number comes from the letters, the quality from the exact size.

Starting on C, a minor second reaches D♭. Its shorthand is m2, and traditionally it counts as dissonance.

How big it is

1 semitoneCD♭0123456789101112
C up to D♭ is 1 semitone. Count the keys, black and white alike.
CCDEFGABCDED♭
C and D♭ on the keyboard.
𝄞CD♭
C up to D♭ written on the treble stave.

Turned upside down

Move the lower note up an octave and a minor second becomes a major seventh. The two numbers add up to nine, and the quality flips — major with minor, augmented with diminished, while perfect stays perfect.

Where you meet it

  • The leading tone resolving to the tonic
  • Adjacent white keys E–F and B–C

From every starting note

FromUp a minor second
CD♭
C♯D
DE♭
D♯E
EF
FG♭
F♯G
GA♭
G♯A
AB♭
A♯B
BC
A dash means the strict spelling would need a triple accidental, which real music avoids by respelling the starting note.

Related

All intervals within an octave