Diminished and Augmented Chords on Guitar, Explained

Most of the chords you play are major or minor. Every so often, though, a chord sheet throws in something like C#dim7 or Caug, and suddenly the song has a twist: a moment of tension, a dramatic turn, a dreamy lift. Those are diminished and augmented chords, the spice of harmony.

They sound exotic, but they're easy to understand and there are only a handful of shapes to learn. This guide explains how they're built, how to play them, and how to use them in real progressions.

How major and minor chords compare

All four basic chord types are built from a root, a third and a fifth. What changes is the size of the intervals:

Chord type	Third	Fifth	Example on C	Sound
Major	Major (4 frets)	Perfect (7 frets)	C E G	Bright, stable
Minor	Minor (3 frets)	Perfect (7 frets)	C E♭ G	Dark, stable
Diminished	Minor (3 frets)	Diminished (6 frets)	C E♭ G♭	Tense, unstable
Augmented	Major (4 frets)	Augmented (8 frets)	C E G#	Dreamy, unresolved

So a diminished chord is a minor chord with its fifth lowered, and an augmented chord is a major chord with its fifth raised. If you've read our guide to major vs minor chords, this is the next step.

Diminished chords

The diminished family has three members you'll see on chord charts:

• Diminished triad (dim or °): root, minor third, diminished fifth. Bdim = B, D, F.
• Diminished seventh (dim7 or °7): adds a diminished seventh. Bdim7 = B, D, F, A♭. Every note is exactly three frets from the next.
• Half-diminished (m7♭5 or ø): adds a minor seventh instead. Bm7♭5 = B, D, F, A. Common in jazz and minor keys.

In practice, guitarists play the diminished 7th most often, even when a chart just says "dim," because it's easy to finger and sounds fuller.

Diminished shapes

• Bdim (triad): root on the A string. Mute the low E and high e.
• Cdim7: root on the A string, 3rd fret. A compact, very useful shape.
• F#dim7: root on the low E string. Mute the A and high e strings.
• D#dim7: on the top four strings. The easiest dim7 shape and the one to learn first.

The diminished 7th repeats every three frets

Here's the magic: because every note in a dim7 chord is three frets apart, the same shape moved up three frets contains the same four notes. D#dim7, F#dim7, Adim7 and Cdim7 are all the same notes in a different order. That means:

• There are really only three different dim7 chords in all of music.
• Any dim7 shape can be slid up or down three frets and still be "correct."
• Sliding the shape in steps of three frets is a classic dramatic effect.

Augmented chords

An augmented chord (aug or +) is root, major third and raised fifth. Caug = C, E, G#. Its notes are each four frets apart, so it's also symmetrical: Caug, Eaug and G#aug contain the same three notes, and the shape repeats every four frets.

• Caug: like an open C, but with the G string at the 1st fret (G#). Strum from the A string.
• Eaug: the same idea with the open low E added. Strum all six.
• Gaug: G in the bass, then D#, G and B. Mute the A string and high e.

How to use diminished chords

1. As a passing chord

The most common use: put a dim7 chord one fret below the chord you're heading to. Its notes slide into the next chord by half steps, creating a smooth, dramatic connection.

Progression	What happens
C – C#dim7 – Dm – G	The bass climbs C – C# – D
G – G#dim7 – Am – D	The bass climbs G – G# – A
F – F#dim7 – G – C	The bass climbs F – F# – G

Play the dim7 for just a beat or two. It's a doorway, not a destination.

2. As a stand-in for the V7 chord

A diminished chord built on the 7th note of a key contains most of the V7 chord's notes. In C major, Bdim (B, D, F) is almost a G7 (G, B, D, F) without the G. That's why the vii° chord leads so strongly back to the home chord.

3. For suspense

Slide a dim7 shape up the neck three frets at a time while strumming: instant movie-villain tension. It's a staple of old film scores, surf rock and dramatic intros.

How to use augmented chords

1. Between I and IV

The raised fifth of an augmented chord wants to rise one more fret. That makes it a perfect bridge from a chord to the chord a fourth higher: C – Caug – F, or G – Gaug – C. The G# in Caug pushes up to the A in F.

2. The rising line

Play C, then Caug, then C6 (which you can play as Am/C), then C7. One note climbs G – G# – A – B♭ while the rest of the chord stays put. This "line cliché" is a classic sound in pop ballads, jazz standards and theme songs.

3. As a dreamy color

Held on its own, an augmented chord sounds floating and unresolved, like a question. Used sparingly, it adds a magical, slightly surreal moment.

Diminished and augmented in keys

• Major keys have one diminished chord, on the 7th note: Bdim in C, F#dim in G. See chords in the key of C.
• Minor keys have a diminished chord on the 2nd note: Bdim in A minor. The harmonic minor scale also produces an augmented chord (Caug in A minor).
• Augmented chords don't occur naturally in major keys. They're added for color.

Reading the symbols

Symbol	Chord
Cdim, C°	C diminished triad (often played as dim7)
Cdim7, C°7	C diminished seventh
Cm7♭5, Cø	C half-diminished
Caug, C+, C(#5)	C augmented

Our guide to guitar chord names covers every symbol you'll meet, and seventh chords explains the other kinds of 7th.

Practice ideas

1. Learn the top-string dim7 (the D#dim7 shape) and slide it up in steps of three frets.
2. Play C – C#dim7 – Dm – G slowly, then G – G#dim7 – Am – D.
3. Play C – Caug – F and listen to the G# rising into A.
4. Try the line cliché: C – Caug – C6 – C7 – F.
5. Add one to a song you know: find a place where the bass could climb a half step and insert a dim7.

Use these chords sparingly. One well-placed diminished or augmented chord can transform a song; five in a row sounds like a cartoon.

For more theory explained simply, see music theory for guitar beginners.

Quick reference: shapes and uses

Chord	Easy shape	Typical use
dim7 (top four strings)	xx1212 and moves in steps of three frets	Passing chord one fret below the next chord
dim7 (A-string root)	x3424x (Cdim7)	Passing chord; dramatic accents
dim triad	x2343x (Bdim)	The vii° chord leading to I
m7♭5	x2323x (Bm7♭5)	Jazz and minor keys, leading to V7
aug	x32110 (Caug)	Between I and IV; rising lines

Common mistakes

• Holding a diminished chord too long. It's a doorway. A beat or two is usually enough.
• Using them everywhere. One per section is plenty; more starts to sound like a cartoon soundtrack.
• Strumming muted strings. Many of these shapes skip strings. Mute them with your fretting fingers.
• Forgetting the symmetry. If a dim7 shape is awkward, slide it three frets for an easier version of the same chord.

Training your ear

The best way to remember these chords is to hear them in context. Play C, then Caug, then F: listen for the one note that rises. Then play C, C#dim7, Dm: listen for the bass climbing a half step at a time. Do this every day for a week, and you'll start recognizing these sounds in songs, film scores and jazz standards. A useful test: diminished chords sound tense and dark, like something is about to happen; augmented chords sound dreamy and floating, like a question with no answer yet.

Fretwork's path covers chord theory like this alongside the shapes themselves, so you always know why a chord works. The first two stages are free, no card required.

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