September Song by Kurt Weill

Overview

Key: C major · Chords used: 20 · Sections: 4

Form: A Section → A Section → Bridge → A Section

Where these chords come from: a chord chart of this song written by a musician and shared on the iReal Pro forums, archived in the iReal Pro forum charts archived in ChoCo (de Berardinis et al., 2023). It's one musician's reading of the song, not a transcription checked against the recording. This page shows that chart as-is: the analysis below is generated directly from it by code, not written by AI. Consecutive repeats of a chord are shown once, and the piano voicings are our playable arrangement of each chord symbol, not a note-for-note transcription.

Section by section

A Section 1

• Am7♭5 – A♭7 – Cmaj7/G – E7/G♯ – Am7 – D7 – Dm7♭5 – G7♭9 – Cmaj7 – C6 – C6/B
  viø7 – bVI7 – Imaj⁴₃ – III⁶₅ – vi7 – II7 – iiø7 – V7b9 – Imaj7 – I6 – I6 (bass B)

A Section 2

• Am7♭5 – A♭7 – Cmaj7/G – E7/G♯ – Am7 – D7 – Dm7♭5 – G7♭9 – Cmaj7 – C6 – C6/D – C6/E
  viø7 – bVI7 – Imaj⁴₃ – III⁶₅ – vi7 – II7 – iiø7 – V7b9 – Imaj7 – I6 – I6 (bass D) – I6 (bass E)

Bridge

• Fm6 – F♯dim7 (×2)
  iv6 – #iv°7
• C6 – C6/B
  I6 – I6 (bass B)

A Section 3

• Am7♭5 – A♭7 – Cmaj7/G – E7/G♯ – Am7 – Am7/G – F♯m7♭5 – Fm7 – B♭7 – C6 – Dm7♭5 – C6 – C6/C – C6/B – C6 – Dm7♭5 – C6
  viø7 – bVI7 – Imaj⁴₃ – III⁶₅ – vi7 – vi⁴₂ – #ivø7 – iv7 – bVII7 – I6 – iiø7 – I6 – I6 – I6 (bass B) – I6 – iiø7 – I6

Chord vocabulary

Chord	Roman numeral	Role	Heard in
Am7♭5	viø7	Outside the key (chromatic)	A Section
A♭7	bVI7	Outside the key (chromatic)	A Section
Cmaj7/G	Imaj⁴₃	Home chord (tonic)	A Section
E7/G♯	III⁶₅	Secondary dominant (V/vi)	A Section
Am7	vi7	In the key	A Section
D7	II7	Outside the key (chromatic)	A Section
Dm7♭5	iiø7	Borrowed from C minor	A Section
G7♭9	V7b9	Borrowed from C minor	A Section
Cmaj7	Imaj7	Home chord (tonic)	A Section
C6	I6	Home chord (tonic)	A Section, Bridge
C6/B	I6 (bass B)	Home chord (tonic)	A Section, Bridge
C6/D	I6 (bass D)	Home chord (tonic)	A Section
C6/E	I6 (bass E)	Home chord (tonic)	A Section
Fm6	iv6	Borrowed from C minor	Bridge
F♯dim7	#iv°7	Outside the key (chromatic)	Bridge
Am7/G	vi⁴₂	In the key	A Section
F♯m7♭5	#ivø7	Outside the key (chromatic)	A Section
Fm7	iv7	Borrowed from C minor	A Section
B♭7	bVII7	Borrowed from C minor	A Section
C6/C	I6	Home chord (tonic)	A Section

Harmonic highlights

• Dm7♭5 (iiø7) is borrowed from the parallel key, C minor.
• G7♭9 (V7b9) is borrowed from the parallel key, C minor.
• Fm6 (iv6) is borrowed from the parallel key, C minor.
• Fm7 (iv7) is borrowed from the parallel key, C minor.
• B♭7 (bVII7) is borrowed from the parallel key, C minor.
• E7/G♯ acts as V/vi: it resolves to Am7.

Sources & accuracy

• Chords: the iReal Pro forum charts archived in ChoCo (de Berardinis et al., 2023). Community chord chart “September Song-Rev JE” (credited “Weill Kurt”, style Ballad) from the forum file linked here, CC BY 4.0 via ChoCo. Performer/songwriter confirmed from Wikidata.
• Section names: from the chart's own markings: section names written on the chart (Intro, Verse, Chorus…) are kept, and rehearsal letters are shown as “A Section”, “B Section” and so on (the B of an AABA song is called the Bridge).
• Cross-check: the iReal Pro forum charts archived in ChoCo (de Berardinis et al., 2023). Community chord chart “September Song-Rev JE” (credited “Weill Kurt”, style Ballad) from the forum file linked here, CC BY 4.0 via ChoCo. Performer/songwriter confirmed from Wikidata. A separately posted chart of the same song; its chords match this page's closely when both are read in the same key (similarity 100%).
• Chord charts are often written in a key that suits a particular singer or band, so this may not be the key of the original recording.
• About the song: Wikipedia.
• Verified: two community charts of this song, posted in different forum threads, agree on its harmony. They're still charts, not transcriptions checked against the recording.
• Rhythm and chord durations aren't shown; each step is one chord change.