Notes, Semitones, and Intervals Explained for Guitar

A semitone (also called a half step) is the smallest distance between two notes in Western music. On guitar, one semitone equals one fret.

Moving from fret 3 to fret 4 on any string is one semitone. Moving from an open string to fret 1 is also one semitone. This consistency makes guitar logical once you understand it.

Remember: B to C and E to F are natural semitones. There is no sharp between them. All other adjacent natural notes have a sharp (or flat) between them.

A whole tone (also called a whole step) equals two semitones. On guitar, this means moving two frets.

Whole tones and semitones are the building blocks of scales. The specific pattern of whole and half steps defines what type of scale you are playing. More on this in the next article.

An interval is the distance between any two notes. Semitones and whole tones are the smallest intervals. Larger intervals have specific names based on how many semitones they span.

Intervals are named using numbers (2nd, 3rd, 4th, etc.) and qualities (major, minor, perfect). The number indicates the scale degree distance. The quality indicates the exact number of semitones.

Each interval has a distinct sound character. Some sound stable and pleasant (consonant). Others sound tense and unstable (dissonant). Neither is better. Both are essential to music.

The perfect 5th is the most stable interval after the octave. It appears in power chords and gives them their strong, open sound. The tritone (6 semitones) is the most unstable. It creates tension that wants to resolve.

Major intervals tend to sound bright and happy. Minor intervals tend to sound dark and sad. This is why major chords feel uplifting and minor chords feel melancholic.

On guitar, intervals create geometric shapes. Learn these shapes and you can play any interval from any starting note.

Common shapes to memorize:

• Octave: Two strings down, two frets up (or three frets when crossing B string)
• Perfect 5th: One string down, two frets up (or same fret on the next string for E-A, A-D, D-G, B-E)
• Major 3rd: One string down, one fret back (except G to B where it is the same fret)

Scales are patterns of intervals. Chords are intervals stacked together. Melodies move through intervals. Everything in music theory reduces to interval relationships.

When you learn a scale, you are learning a specific sequence of intervals from a root note. When you learn a chord shape, you are learning which intervals are played together. When you solo, you are choosing which intervals sound good over a given chord.

Interval recognition also trains your ear. Musicians who can identify intervals by sound can figure out songs quickly, improvise more naturally, and communicate musical ideas precisely.

You do not need to master all intervals immediately. Start with the basics: octave, fifth, major third, minor third. These four intervals will take you far.