Tritone: the "devil's interval", heard and explained
The tritone is 6 semitones, exactly half an octave. Play it, hear it in Maria and The Simpsons theme, and learn the real story of the devil's interval.
A tritone is an interval of 6 semitones (three whole tones), exactly half an octave, such as C up to F sharp. Spelled C to F sharp it is an augmented fourth; spelled C to G flat it is a diminished fifth. It sounds tense and unresolved, and opens the song Maria from West Side Story.
Listen to a tritone
C to F♯: 6 semitones.
What does a tritone sound like?
Restless and ambiguous: it seems to want to move somewhere. Inside a dominant seventh chord (G B D F, with B to F a tritone) it is the tension that pulls toward the tonic.
Songs that start with a tritone
| Song | Direction | Where |
|---|---|---|
| Maria (West Side Story) | Up | the first two notes |
| The Simpsons Theme | Up | from the 1st to the 3rd note |
| Black Sabbath (Black Sabbath) | Down | from the 2nd to the 3rd note of the main riff |
Titles only. Each melody's opening was checked note by note; songs we were not sure of are left out.
How do you recognise a tritone by ear?
- The tritone splits the octave in half, so it sounds the same size going up or down: C to F sharp and F sharp to C are both tritones.
- Sing a perfect fifth and come down a half step, or a perfect fourth and go up a half step: you land on the tritone.
- The first two notes of Maria are the classic anchor; the next note resolves up a half step to a fifth.
Quick test: tritone or not?
Four sounds. Each one is a tritone or one of the intervals people confuse it with. Listen, then pick.
Score: / 4 (your score updates as you answer)
The tritone on every note
Intervals are spelled by letter: a tritone always spans 4 letter names, which is why the top note is sometimes a sharp or a flat.
| From | Tritone up | Spelled as diminished fifth | Hear it |
|---|---|---|---|
| C | F♯ | G♭ | |
| D♭ | G | A♭♭ | |
| D | G♯ | A♭ | |
| E♭ | A | B♭♭ | |
| E | A♯ | B♭ | |
| F | B | C♭ | |
| F♯ | B♯ | C | |
| G | C♯ | D♭ | |
| A♭ | D | E♭♭ | |
| A | D♯ | E♭ | |
| B♭ | E | F♭ | |
| B | E♯ | F |
Tritone in numbers
| Measure | Value |
|---|---|
| Semitones | 6 |
| Size on a piano (equal temperament) | 600 cents |
| Pure (just) ratio | 45:32 = 590.2 cents |
| Piano vs pure | +9.8 cents |
| Inversion | Tritone (6 semitones) |
Why is it called the devil's interval?
The nickname diabolus in musica ("the devil in music") is old, but no medieval source using it for the tritone is known; the related older phrase mi contra fa describes clashes like this one. Medieval singers avoided it because it is hard to sing and unstable in the modal system; stories that the Church banned it or punished singers are not supported by evidence.
Frequently asked questions
How many semitones are in a tritone?
Six: exactly half of the 12 semitones of an octave, or three whole tones (hence the name).
Is a tritone an augmented fourth or a diminished fifth?
Both, depending on spelling. C to F sharp spans four letter names, so it is an augmented fourth; C to G flat spans five, so it is a diminished fifth. On a piano they are the same keys.
Why is the tritone called the devil's interval?
Because of the Latin nickname diabolus in musica. It reflects how unstable the interval sounded in older music, not a church ban: no decree forbidding it is known.
What is the inversion of a tritone?
Another tritone. 6 + 6 = 12 semitones, so the tritone is the only interval that maps onto itself when inverted.
What song starts with a tritone?
Maria from West Side Story starts with a rising tritone. The Simpsons theme outlines one between its first and third notes.