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In some of our previous tutorials we have discussed stacking thirds to create triads and chords, but what exactly is a third? What are intervals?

We shall investigate what intervals are and how they are named. We shall also look at interval quality, melodic and harmonic intervals along with simple and compound intervals, and the inversion of intervals.

• Interval name

• Interval quality
• Melodic Intervals
• Harmonic Intervals
• Simple Intervals
• Compound Intervals
• Inversion of Intervals

If these things interest you then please consider signing up for the silver membership package where you will get early access to tutorials far more comprehensive than those available to non subscribers and access to downloadable copies of the full tutorials and reference sheets.

What are intervals?

At their core, intervals are simply the distance between two notes.

On a piano, that distance is measured in white and black keys. On a guitar, it’s measured in frets—literal, physical steps under your fingers. One fret is a semitone. Two frets is a whole tone. But the guitar adds something unique: multiple ways to play the same interval, since it is possible to play the same note on multiple strings, each with its own timbre, resonance, and expressive character.

Now we know what an interval is we can learn about how we identify and name them.

What’s in a name?

The naming of an interval involves two parts

• Interval number
• Interval quality

We shall look at these separately.

Naming an interval starts with something very simple: counting the letter names between the two notes. This gives you the numerical part of the interval — 2nd, 3rd, 4th, 5th, and so on. For example, from C to E you count C–D–E, which gives you a 3rd. From A to F you count A–B–C–D–E–F, which gives you a 6th. This step is purely alphabetical and doesn’t yet tell you anything about the sound or quality of the interval. It’s just the structural distance on the musical staff.

Once you know the number, the next step is to determine the quality — major, minor, perfect, augmented, or diminished. This is where the major scale becomes our reference point. Every note in a major scale forms a specific interval above the tonic, and these intervals are the “default” versions. For example, in the C major scale, C to E is a major 3rd, C to G is a perfect 5th, and C to D is a major 2nd. These major‑scale intervals act like a ruler: if the interval you’re analysing matches the major‑scale version, it’s major or perfect; if it’s one semitone smaller, it becomes minor or diminished; if it’s one semitone larger, it becomes augmented

The major scale is the anchor because it defines the natural size of each interval. When you compare any two notes, you mentally place the lower note as the “temporary tonic” and imagine its major scale. Then you check where the upper note would fall. If the upper note matches the major‑scale degree, the interval is major (for 2nds, 3rds, 6ths, 7ths) or perfect (for 4ths, 5ths, octaves). If the upper note is one semitone lower than the major‑scale version, the interval becomes minor (for 2nds, 3rds, 6ths, 7ths) or diminished (for perfect intervals). If it’s one semitone higher, the interval becomes augmented.

This approach works for every key and every pair of notes. For example, from D to F: count D–E–F (a 3rd). Now imagine the D major scale: D–E–F♯–G–A–B–C♯. The major 3rd above D is F♯, but your note is F natural — one semitone lower — so the interval is a minor 3rd. Another example: from G to C♯. Count G–A–B–C (a 4th). In the G major scale, the 4th degree is C natural. Your note is C♯ — one semitone higher — so the interval is an augmented 4^th (or a tritone).

Why This Method Matters

Relating intervals to the major scale gives you a consistent, reliable system that works across instruments and musical styles. It removes guesswork and helps you understand why certain intervals feel stable, tense, bright, or dark. For guitarists, it also connects directly to fretboard logic: once you know the major‑scale shapes in each position, you can instantly visualise interval qualities by comparing them to those shapes. This makes analysis, improvisation, and chord construction far more intuitive.

Understanding Intervals in Steps, Half‑Steps, Tones, and Semitones

Intervals are simply distances between notes. On the guitar, this becomes a straightforward relationship

• 1 fret – 1 semitone (half‑step)
  2 frets – 1 whole tone (whole step)

Everything in interval theory can be measured with those two units.

The Two Units of Measurement

Semitone (Half‑Step)

• The smallest distance in Western music
• On guitar: one fret up or down
• Example: 5th fret → 6th fret

Whole Tone (Whole Step)

• Equal to two semitones
• On guitar: two frets up or down
• Example: 5th fret → 7th fret

Below is a table of the different intervals

Here endeth the lesson for unsubscribed members. To explore the ides of

• Melodic Intervals
• Harmonic Intervals
• Simple Intervals
• Compound Intervals
• Inversion of Intervals

please consider subscribing to silver membership. Silver members have access to more complete tutorials and downloadable pdf versions of both the tutorials and reference sheets designed to allow you to build your own composers reference toolkit.