P4Fourths Hub
Harmonizing in Triads
Lesson 1 of 3

The Four Triad Types

A triad is three notes stacked in thirds: a root, a 3rd, and a 5th. The quality of those two thirds (major or minor) determines whether the triad sounds bright, dark, tense, or floating. There are exactly four combinations, and in fourths tuning each one has a single shape that works everywhere.

The Four Types

TypeFormulaSound
Major1 - 3 - 5Bright and stable. The foundation of tonal music.
Minor1 - b3 - 5Darker and more somber. The 3rd is lowered by one semitone.
Diminished1 - b3 - b5Tense and unstable. Both 3rd and 5th are lowered.
Augmented1 - 3 - #5Mysterious and floating. The 5th is raised by one semitone.

Major and minor triads cover most of tonal music. Diminished triads appear naturally on the 7th degree of the major scale (B-D-F in C major) and function as leading-tone chords. Augmented triads are rarer but show up in chromatic passing motion and in modes like Ionian #5.

Shapes on the Fretboard

Select a root to explore each triad type. The fretboard shows all occurrences of the three notes; the chord charts below show close voicings on adjacent string groups.

C (C E G)

1 - 3 - 5 - Bright and stable. The foundation of tonal music.

F
C
G
D
A
E
3
5
7
9
12
15
17
19
22
F
C
G
D
A
E

Cm (C D# G)

1 - b3 - 5 - Darker and more somber. The 3rd is lowered by one semitone.

F
C
G
D
A
E
3
5
7
9
12
15
17
19
22
F
C
G
D
A
E

Cdim (C D# F#)

1 - b3 - b5 - Tense and unstable. Both 3rd and 5th are lowered.

F
C
G
D
A
E
3
5
7
9
12
15
17
19
22
F
C
G
D
A
E

Caug (C E G#)

1 - 3 - #5 - Mysterious and floating. The 5th is raised by one semitone.

F
C
G
D
A
E
3
5
7
9
12
15
17
19
22
F
C
G
D
A
E

The Fourths Tuning Advantage

One close voicing shape per triad type covers every string group. A C major triad shape on strings E-A-D uses the same fingering on A-D-G, D-G-C, or G-C-F. Four shapes total (major, minor, diminished, augmented) give you complete coverage of the entire neck in every key.

Practice

Pick a root and play all four types in sequence: major, minor, diminished, augmented. Listen to how lowering the 3rd darkens the sound, how lowering the 5th adds tension. Then shift the root up one fret and repeat - the shapes are identical, only the pitch center moves.

Harmonizing the Major Scale