Intervals
Augmented Second
2A · 3 semitones
Three semitones written across two letter names — the exotic leap at the heart of the harmonic minor scale.
Also written A2 · 2A
Augmented Second
2A · 3 semitones
On the piano, from every note
| From | Notes | Play it on your instrument |
|---|---|---|
| C | C – D# | |
| C# | C# – D## | |
| D | D – E# | |
| Eb | Eb – F# | |
| E | E – F## | |
| F | F – G# | |
| F# | F# – G## | |
| G | G – A# | |
| Ab | Ab – B | |
| A | A – B# | |
| Bb | Bb – C# | |
| B | B – C## |
Tap a key or a fret to hear it.
Read on: number and quality · inversion · compound intervals · consonance and dissonance
Every second
A second can take these qualities, one semitone apart; choose one to see the upper note move and hear the pair.
Understanding Augmented Second
Names and symbols
Augmented Second is written A2, 2A: the letter is the quality, the number the size. Chord formulas on this site write the number first, as tonal does.
The augmented second sounds exactly like a minor third, three semitones, and is written only when the two notes are a letter apart — the step from the sixth to the seventh degree of a harmonic minor scale. The spelling says it is a step, not a skip.
How it sounds
An augmented second spans 3 semitones: C – D#. It sounds like a minor third, but its spelling places it inside a scale where the two notes are adjacent degrees rather than a third apart.
Where you will hear it
The harmonic minor scale raises its seventh degree, which opens an augmented second between the sixth and seventh — the interval that gives the scale its distinctive, non-Western colour. It is idiomatic in klezmer, in flamenco, and in any music drawing on the Phrygian dominant mode.
Learn this properly
Chapter 5: IntervalsCommon questions
- How many semitones is an Augmented Second?
- Three — C – D# — the same distance as a minor third, spelled as a second. Count the semitones of any interval with the interval calculator.
- Why is it not just called a minor third?
- Because the two notes sit on adjacent letter names. In A harmonic minor, F to G♯ is a second by function even though it measures three semitones.
- Which scale contains an augmented second?
- The harmonic minor scale, between its sixth and seventh degrees, and its fifth mode, the Phrygian dominant.
- How do I play Augmented Second?
- On guitar the handiest shape is Next string, A 3 · D 1, read as string and fret; the instrument panel draws it from any starting note with the other shapes. On the piano count 3 semitones up from any key, black keys included. Play the notes together for the harmonic form, one after the other for the melodic form.
- What is the inversion of Augmented Second?
- The inversion of Augmented Second is the Diminished Seventh: put the lower note an octave higher and the distance that remains is the inversion. The two always add up to an octave, 3 semitones and 9 semitones, and swap their qualities between major and minor, or keep perfect as perfect.