What Is a Tritone?

A tritone is an interval of six half steps — three whole tones, hence the name — sitting exactly halfway through the octave. A to E♭, or F to B. Medieval theorists nicknamed it diabolus in musica ("the devil in music") for its restless, unresolved sound; metal and film composers use it for exactly that reason.

The shape on the fretboard

One string up, one fret up from a low-string root — a half step past the perfect fourth, a half step short of the perfect fifth shape's reach:

The tension engine of harmony

The tritone isn't just a spooky sound effect — it's the reason chord progressions move. Every dominant seventh chord contains a tritone between its third and seventh, and that internal itch is what makes G7 demand to resolve to C. It shows up between the 4th and 7th degrees of every major scale, which makes it the signature of the dominant function in how chords are built from scales.

Ear anchor: the opening of "The Simpsons" theme ("The Simp-sons"), or "Maria" from West Side Story.

Related terms

• Dominant seventh chord — the tritone's day job
• Consonance & dissonance — where the tritone sits on the spectrum
• Cadence — the resolution the tritone drives