Intervals — The Building Blocks
What an interval is
The exact, unambiguous definition of an interval — measured in half-steps, named by quality and number.
Distance, with a name
An interval is the distance between two notes, measured in half-steps. Each distance has a name made of two parts:
- Quality: major, minor, perfect, augmented, or diminished.
- Number: 2nd, 3rd, 4th, 5th, 6th, 7th, octave (and beyond).
You read it like “major third” or “perfect fifth”. The number comes from counting letter names; the quality comes from the exact half-step count.
Plain-language version
Do not worry about memorising every name immediately. First, hear the idea: play a note, move a few frets, and listen to how the second note feels against the first. That feeling is the interval.
| Half-steps | Name | Shorthand |
|---|---|---|
| 0 | Unison / Perfect 1st | P1 |
| 1 | Minor 2nd | m2 |
| 2 | Major 2nd | M2 |
| 3 | Minor 3rd | m3 |
| 4 | Major 3rd | M3 |
| 5 | Perfect 4th | P4 |
| 6 | Tritone / Augmented 4th / Diminished 5th | TT / ♭5 |
| 7 | Perfect 5th | P5 |
| 8 | Minor 6th | m6 |
| 9 | Major 6th | M6 |
| 10 | Minor 7th | m7 |
| 11 | Major 7th | M7 |
| 12 | Perfect Octave | P8 |
Memorise this table. It is the periodic table of music.
Beginner shortcut
For now, focus on these first: m2 is 1 fret, M2 is 2 frets, m3 is 3 frets, M3 is 4 frets, P4 is 5 frets, and P5 is 7 frets. These cover most beginner chord and scale work.
Counting on the fretboard
On a single string: one fret = one half-step. Count frets to count semitones.
Click any row to animate stepping from R to the target.
Why intervals matter
- A chord is “a stack of intervals from a root.”
- A scale is “a sequence of intervals from a root.”
- A melody is “a path of intervals from note to note.”
- Ear training is learning to recognise each interval by sound.
Get this chapter right and the rest of the site is downhill.