A diminished fifth interval is a musical interval that spans six semitones (half steps) between two notes. It is also known as a tritone because it divides an octave exactly in half. This interval creates a tense, unstable sound that often feels like it wants to resolve to a more stable harmony.
For example, the distance from C to G♭ is a diminished fifth:
- C → D = 2 semitones
- D → E = 2 semitones
- E → F = 1 semitone
- F → G♭ = 1 semitone
Total: 6 semitones
Unlike a perfect fifth, which sounds open and stable, the diminished fifth creates musical tension and is often used to add drama, suspense, or harmonic movement.
What Is a Diminished Fifth Interval?
An interval describes the distance between two musical notes. The diminished fifth is created by lowering a perfect fifth by one semitone.
A perfect fifth contains:
- 7 semitones
- Example: C → G
Lower the fifth note by one semitone:
- C → G becomes C → G♭
The result is:
- C → G♭ = diminished fifth
- Distance = 6 semitones
The name comes from the interval quality:
- Fifth = the note is five scale degrees away
- Diminished = made smaller than the perfect version
How to Build a Diminished Fifth
There are two common ways to identify a diminished fifth.
1. Lower a Perfect Fifth by One Semitone
Start with a perfect fifth:
| Perfect Fifth | Lower by One Semitone | Diminished Fifth |
|---|---|---|
| C – G | G → G♭ | C – G♭ |
| D – A | A → A♭ | D – A♭ |
| E – B | B → B♭ | E – B♭ |
| F – C | C → B | F – B |
Each example contains six semitones.
2. Count Half Steps
A diminished fifth always equals:
6 half steps
Example:
F to B
- F → F♯ = 1
- F♯ → G = 2
- G → G♯ = 3
- G♯ → A = 4
- A → A♯ = 5
- A♯ → B = 6
Therefore:
F–B is a diminished fifth interval.
Diminished Fifth on Piano
On a piano keyboard, a diminished fifth covers six keys upward, counting every black and white key.
Example:
C to G♭
Starting from C:
C → C♯ → D → D♯ → E → F → G♭
The final note is six semitones above C.
Because the distance is exactly half an octave, the interval creates a strong sense of instability.
Diminished Fifth on Guitar
On guitar, a diminished fifth can be found by moving six frets on the same string.
Example:
- Play C on the 8th fret of the low E string
- Move six frets higher
- The note becomes G♭
The distance between these notes is a diminished fifth.
Guitarists often encounter this interval inside diminished chords and heavy or experimental styles of music because of its tense sound.
Diminished Fifth vs Tritone: Are They the Same?
The diminished fifth and the tritone are closely related, but they describe the interval from different perspectives.
A tritone means any interval covering three whole tones:
- 3 whole tones × 2 semitones = 6 semitones
A diminished fifth is one specific spelling of that distance.
Example:
- C → G♭ = diminished fifth
- C → F♯ = augmented fourth
Both contain six semitones, so both are tritones.
The difference is the note spelling:
| Interval | Notes | Distance |
|---|---|---|
| Diminished fifth | C – G♭ | 6 semitones |
| Augmented fourth | C – F♯ | 6 semitones |
| Tritone | Any six-semitone interval | 6 semitones |
The sound is identical on equal-tempered instruments, but the theoretical function can differ depending on the musical context.
Diminished Fifth vs Perfect Fifth
The perfect fifth is one of the most stable intervals in music. The diminished fifth is much more tense.
| Feature | Perfect Fifth | Diminished Fifth |
|---|---|---|
| Distance | 7 semitones | 6 semitones |
| Example | C–G | C–G♭ |
| Sound | Open and stable | Tense and unstable |
| Harmonic role | Creates stability | Creates tension |
| Common use | Melodies, chords, harmony | Diminished chords, dramatic effects |
A single semitone difference completely changes the character of the interval.
You can explore how perfect fifths work in music through the guide on perfect fifth intervals.
Why Does a Diminished Fifth Sound Unstable?
The diminished fifth creates tension because the two notes are separated by a distance that does not strongly reinforce a single harmonic center.
In traditional harmony, this tension often resolves:
Example:
B–F inside a diminished chord may resolve toward:
- C major harmony
- A minor harmony
- Other stable chord tones
The listener naturally expects movement because the interval feels unresolved.
This quality made the tritone historically famous as the “devil’s interval,” although that nickname is more cultural than a technical description of how the interval functions in music.
How Musicians Use the Diminished Fifth
The diminished fifth appears in many musical situations.
Diminished Chords
A diminished chord contains a diminished fifth between its root and diminished fifth note.
Example:
B diminished chord:
- B
- D
- F
The distance:
B → F = diminished fifth
You can learn more about how this interval functions inside chords in the guide to diminished chords explained.
Creating Musical Tension
Composers and songwriters use diminished fifth intervals to create:
- Suspense
- Darkness
- Uncertainty
- Dramatic transitions
The interval is especially common in:
- Classical harmony
- Film music
- Jazz
- Progressive music
- Experimental compositions
Building Harmonic Understanding
Understanding diminished fifths helps musicians understand:
- Chord construction
- Harmonic movement
- Scale relationships
- Diminished chord structures
Intervals are the foundation of chords and scales, which is why learning them makes music theory easier to understand.
How to Recognize a Diminished Fifth by Ear
A diminished fifth has a distinctive tense sound.
Try this practice method:
- Play a perfect fifth (C–G).
- Notice its stable, open quality.
- Lower the second note by one semitone.
- Compare C–G♭.
The diminished fifth should sound:
- More tense
- Less settled
- More likely to require resolution
A useful exercise is comparing it with other intervals such as thirds and perfect fifths until your ear recognizes the six-semitone distance.
Frequently Asked Questions
How many semitones are in a diminished fifth?
A diminished fifth contains six semitones (half steps).
Is a diminished fifth the same as a tritone?
A diminished fifth is one type of tritone. Both contain six semitones, but a tritone is a broader term that also includes the augmented fourth.
What notes make a diminished fifth?
Any two notes separated by six semitones and spelled as a fifth can create a diminished fifth, such as C–G♭ or B–F.
Why does a diminished fifth sound dissonant?
Because its six-semitone distance creates harmonic tension and lacks the stability of intervals such as the perfect fifth.
Is a diminished fifth used in chords?
Yes. It appears in diminished chords, where it helps create their characteristic tense sound. You can also explore related chord structures through types of triads.
Liam Turner is a guitar theory writer and chord analysis specialist at Chord Calculator. He focuses on chord construction, music theory, scale relationships, harmony tools, and guitar learning resources for musicians, producers, songwriters, and beginners. Liam creates practical, easy-to-follow content around chord progressions, interval formulas, key analysis, and interactive music tools to help users better understand harmony, songwriting, and instrument practice.