Guide

Music theory fundamentals, for people who make tracks

Updated August 1, 2026

Theory is not a rulebook. It is a description, written after the fact, of patterns that people kept finding pleasant — and knowing the description lets you reach for a sound on purpose instead of by accident. This is the portion of it that changes what you write, in the order it becomes useful.

Twelve notes, and why twelve

Double a frequency and you get the same note again, higher. 110 Hz and 220 Hz are both A; the ear treats them as versions of one thing. That doubling is an octave, and it is the one interval nearly every musical culture agrees on.

Western music cuts that octave into twelve equal steps, called semitones. Equal here is literal and multiplicative: each step raises the frequency by the twelfth root of two, about 1.0595. Twelve of them multiply back to exactly 2, which is the octave. That system is 12-tone equal temperament, and it is what your synth, your keyboard and your piano roll are all built on.

Reference pitch is A4 = 440 Hz. Everything else is arithmetic from there, which is worth knowing because it tells you where your low end actually lives:

If you write a sub-bass on E1, its fundamental is at 41 Hz — below what most laptop speakers and phone speakers reproduce at all. That is a compositional decision as much as a mixing one.

Intervals are just distances

An interval is the gap between two notes, counted in semitones. The names are old and slightly illogical, but the counting is not:

Two are worth memorising by sound before anything else: the perfect 5th, which is what a power chord is and what makes a bassline feel grounded, and the 3rd, because the difference between the major and the minor version is a single semitone and it is the entire emotional content of most chords. There is an interval and chord trainer on this site for exactly this, and it is free.

Scales pick seven of the twelve

A scale is a choice of which notes are in play. The major scale is a fixed pattern of steps from its root — in semitones, 2 2 1 2 2 2 1. Start on C and that pattern gives you exactly the white keys: C D E F G A B.

The natural minor scale is the same twelve notes reorganised around a different centre: 2 1 2 2 1 2 2. Start on A and you also get the white keys: A B C D E F G.

That is not a coincidence, and the consequences are the most useful thing on this page. They are below.