How many semitones is an augmented eleventh?

A Augmented Eleventh spans 18 semitones: C – F#. Count the semitones of any interval with the interval calculator.

What is the ♯11 sound?

The Lydian colour: a major chord with a raised fourth. It floats rather than resolves, which is why it carries so much film and fusion writing.

What is a compound interval?

Any interval wider than an octave. A Augmented Eleventh is an octave plus an augmented fourth, and it keeps the character of that simple interval in a more open, less congested form.

How do I play Augmented Eleventh?

On guitar the handiest shape is Next string, B 1 · E 14, read as string and fret; the instrument panel draws it from any starting note with the other shapes. On the piano count 18 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 Eleventh?

The inversion of Augmented Eleventh is the Diminished Fifth: put the lower note an octave higher and the distance that remains is the inversion. The two always add up to an octave, 18 semitones and 6 semitones, and swap their qualities between major and minor, or keep perfect as perfect.

Augmented Eleventh Interval: How It Sounds, with Song Examples

Play it on your instrument

Loading the keyboard…

From

On the piano, from every note

From	Notes	Play it on your instrument
C	C – F#
C#	C# – F##
D	D – G#
Eb	Eb – A
E	E – A#
F	F – B
F#	F# – B#
G	G – C#
Ab	Ab – D
A	A – D#
Bb	Bb – E
B	B – E#

Tap a key or a fret to hear it.

Number and quality

An interval has two names. The number counts the letter names from the lower note to the upper one, and the quality counts the semitones inside that number. Augmented Eleventh spans 11 letter names, which makes it a eleventh, and 18 semitones, which makes it augmented.

DLetter
ELetter
FLetter
GLetter
ALetter
BLetter
CLetter
DLetter
ELetter
18 semitones

Read on: number and quality · inversion · compound intervals · consonance and dissonance

Every eleventh

A eleventh can take these qualities, one semitone apart; choose one to see the upper note move and hear the pair.

Where it lives

Augmented Eleventh is in every chord whose formula includes 11A from the root, in every scale that includes it from the tonic, and between these pairs of notes in a major key.

Scales that contain it

C LydianC · D · E · F# · G · A · B
C Whole ToneC · D · E · F# · G# · A#
C AlteredC · Db · D# · E · F# · Ab · Bb
C Lydian DominantC · D · E · F# · G · A · Bb
C Half-Whole DiminishedC · Db · Eb · E · F# · G · A · Bb

In C major

F–B

Related intervals

The intervals one step from Augmented Eleventh: its inversion, the same sound spelled differently, its simple or compound form, and its nearest neighbours in size.

Diminished Fifth5d · 6 semitones · C – Gb
Inversion: together they make an octave
Diminished Twelfth12d · 18 semitones · C – Gb
The same sound, spelled differently
Tritone4A · 6 semitones · C – F#
The simple form, an octave narrower
Perfect Eleventh11P · 17 semitones · C – F
One size away
Perfect Twelfth12P · 19 semitones · C – G
One size away

Open it in a tool

Understanding Augmented Eleventh

Names and symbols

Augmented Eleventh is written A11, 11A: the letter is the quality, the number the size. Chord formulas on this site write the number first, as tonal does.

A compound interval is a simple interval plus an octave, and the two names are used interchangeably in chord symbols: a 9th in a chord is the 2nd of the scale an octave up, an 11th the 4th, a 13th the 6th. The compound name says the note sits above the seventh.

How it sounds

A Augmented Eleventh spans 18 semitones: C – F#. It is an octave plus an augmented fourth, and compound intervals keep the quality of the simple interval inside them while losing much of its edge — the extra octave gives the two notes room to stop interfering with each other.

The tritone opened out by an octave, where it loses its urgency and becomes pure colour.

How it is used

The ♯11 is the Lydian sound — bright, floating and unmistakable in film scoring. On a maj7♯11 it adds lift without any pull toward resolution.

Learn this properly

Chapter 5: Intervals

Common questions

How many semitones is an augmented eleventh?: A Augmented Eleventh spans 18 semitones: C – F#. Count the semitones of any interval with the interval calculator.
What is the ♯11 sound?: The Lydian colour: a major chord with a raised fourth. It floats rather than resolves, which is why it carries so much film and fusion writing.
What is a compound interval?: Any interval wider than an octave. A Augmented Eleventh is an octave plus an augmented fourth, and it keeps the character of that simple interval in a more open, less congested form.
How do I play Augmented Eleventh?: On guitar the handiest shape is Next string, B 1 · E 14, read as string and fret; the instrument panel draws it from any starting note with the other shapes. On the piano count 18 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 Eleventh?: The inversion of Augmented Eleventh is the Diminished Fifth: put the lower note an octave higher and the distance that remains is the inversion. The two always add up to an octave, 18 semitones and 6 semitones, and swap their qualities between major and minor, or keep perfect as perfect.