Guitar Intervals: A Simple Explanation Without the Extra Theory
On the fretboard it is useful to measure pitch distance in semitones first, but a complete interval name also depends on the number of note letters involved. The same six semitones can therefore be spelled as an augmented fourth or a diminished fifth: they sound alike in equal temperament but describe different harmonic functions.
A semitone is one fret, no more, no less
Neighboring frets on one string are always a semitone apart - that's the smallest unit of pitch on a guitar. An interval of two frets is a whole tone (two semitones), three frets is a tone and a half, and so on. Counting intervals physically is literally counting frets between two notes.
Names for the most common intervals
Every distance in semitones has its own name - here are the most commonly used:
- 0 semitones - unison (the same note).
- 3 semitones - minor third (sounds "minor", sad).
- 4 semitones - major third (sounds "major", bright).
- 5 semitones - perfect fourth.
- 7 semitones - perfect fifth (the most stable, "open" interval after the unison).
- 12 semitones - octave (the same note an octave higher).
A chord is several intervals from the root at once
A major chord (see the article on connecting chords and scales) is the root plus a major third plus a perfect fifth. A minor chord is the root plus a minor third plus a perfect fifth. The physical difference between major and minor is exactly one semitone, in exactly one interval - the third.
A power chord is an interval, not a chord in the full sense
A power chord (see the article on power chords) is only the root and the fifth - it has no third at all, which is why it has no major or minor color. It's literally a single interval (a fifth), not a full triad.
A scale is a sequence of intervals from the tonic
A major scale is one specific, always-the-same sequence of intervals from the tonic (see the article on CAGED for how that lays out on the neck): it's the order of major and minor intervals between neighboring degrees, not the notes themselves, that makes a scale major, minor, or pentatonic, for instance.
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