🎵 Music Theory

Chord Construction

How every chord type is built from intervals — visualized

Interval Color Key

1
Root
2
Major 2nd
3
Major 3rd
♭3
Minor 3rd
4
Perfect 4th
5
Perfect 5th
♭5
Diminished 5th
#5
Augmented 5th
7
Major 7th
♭7
Minor 7th
𝄫7
Diminished 7th
9
9th (2nd up an octave)
Basic Triads — 3 Notes
Major
C, D, G, etc.
1
3
5
Key of C
C – E – G
Minor
Cm, Dm, Am, etc.
1
♭3
5
Key of C
C – E♭ – G
Diminished
Cdim, Ddim, etc.
1
♭3
♭5
Key of C
C – E♭ – G♭
Augmented
Caug, C+, etc.
1
3
#5
Key of C
C – E – G#
Seventh Chords — 4 Notes
Major 7
Cmaj7, Fmaj7, etc.
1
3
5
7
Key of C
C – E – G – B
Dominant 7
C7, G7, A7, etc.
1
3
5
♭7
Key of C
C – E – G – B♭
Minor 7
Cm7, Am7, etc.
1
♭3
5
♭7
Key of C
C – E♭ – G – B♭
Minor Major 7
CmMaj7, etc.
1
♭3
5
7
Key of C
C – E♭ – G – B
Half-Diminished
Cø, Cm7♭5, etc.
1
♭3
♭5
♭7
Key of C
C – E♭ – G♭ – B♭
Diminished 7
Cdim7, C°7, etc.
1
♭3
♭5
𝄫7
Key of C
C – E♭ – G♭ – B𝄫
Augmented Maj 7
Cmaj7#5, etc.
1
3
#5
7
Key of C
C – E – G# – B
Augmented 7
C7#5, C+7, etc.
1
3
#5
♭7
Key of C
C – E – G# – B♭
Suspended Chords — No 3rd
Suspended 2
Csus2, Dsus2, etc.
1
2
5
Key of C
C – D – G
Suspended 4
Csus4, Dsus4, etc.
1
4
5
Key of C
C – F – G
7sus4
C7sus4, G7sus4, etc.
1
4
5
♭7
Key of C
C – F – G – B♭
Extended Chords — Adding Color
Dominant 9
C9, G9, etc.
1
3
5
♭7
9
Key of C
C – E – G – B♭ – D
Major 9
Cmaj9, Fmaj9, etc.
1
3
5
7
9
Key of C
C – E – G – B – D
Minor 9
Cm9, Am9, etc.
1
♭3
5
♭7
9
Key of C
C – E♭ – G – B♭ – D
Dominant 11
C11, G11, etc.
1
3
5
♭7
9
11
Key of C
C – E – G – B♭ – D – F
Dominant 13
C13, G13, etc.
1
3
5
♭7
9
11
13
Key of C
C – E – G – B♭ – D – F – A

Quick Reference — All Chord Formulas

Chord TypeFormulaSymbolNotes (C)
Major1 – 3 – 5CC E G
Minor1 – ♭3 – 5CmC E♭ G
Diminished1 – ♭3 – ♭5CdimC E♭ G♭
Augmented1 – 3 – #5C+C E G#
Major 71 – 3 – 5 – 7Cmaj7C E G B
Dominant 71 – 3 – 5 – ♭7C7C E G B♭
Minor 71 – ♭3 – 5 – ♭7Cm7C E♭ G B♭
Minor Major 71 – ♭3 – 5 – 7CmMaj7C E♭ G B
Half-Diminished1 – ♭3 – ♭5 – ♭7CøC E♭ G♭ B♭
Diminished 71 – ♭3 – ♭5 – 𝄫7C°7C E♭ G♭ B𝄫
Sus21 – 2 – 5Csus2C D G
Sus41 – 4 – 5Csus4C F G
Dominant 91 – 3 – 5 – ♭7 – 9C9C E G B♭ D
Major 91 – 3 – 5 – 7 – 9Cmaj9C E G B D
Minor 91 – ♭3 – 5 – ♭7 – 9Cm9C E♭ G B♭ D

How Chord Construction Works

Every chord is built by stacking specific intervals on top of a root note. The root is your starting point — the note that gives the chord its name. From there, you add notes at specific distances (intervals) above the root to create the chord's unique sound.

The Major Scale — Your Starting Point

Chord formulas are based on the major scale. When you see "1 – 3 – 5" for a major chord, those numbers refer to the 1st, 3rd, and 5th notes of the major scale built on the root. For a C major chord: the C major scale is C–D–E–F–G–A–B, so 1=C, 3=E, 5=G. That gives you C–E–G.

Flats and Sharps in Formulas

When you see a ♭ (flat) in a formula, it means you lower that scale degree by one half step. A ♭3 means you take the 3rd of the major scale and lower it by one fret. A #5 means you raise the 5th by one fret. This is how we get the different chord qualities — major, minor, diminished, and augmented all use the same root but change which intervals are natural, flatted, or sharped.

Triads vs. Seventh Chords vs. Extended

Triads use three notes (1, 3, 5 with variations). Seventh chords add a fourth note — some type of 7th interval. Extended chords keep going: 9ths, 11ths, and 13ths stack even more intervals on top. The more notes you add, the more complex and colorful the chord sounds.

Why Suspended Chords Sound Different

Suspended chords replace the 3rd with either a 2nd (sus2) or 4th (sus4). Since the 3rd is what makes a chord sound major or minor, removing it creates an open, unresolved quality — the chord feels like it wants to "resolve" back to major or minor. That tension is why sus chords are so useful in songwriting.

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