Thirds & fifths

Musicians measure distance in semitones. Three distances matter more than all others, because chords are built from them:

MINOR 3rd = 3 semitones. MAJOR 3rd = 4 semitones. PERFECT 5th = 7 semitones.

To find one: start on your note and count semitones upward, counting every key. From C: 4 semitones up is E (major 3rd), 7 up is G (perfect 5th).

The perfect 5th is worth memorising as a shape: from any white key it is usually white-to-white, four white keys apart (C→G, D→A…).

m3 = 3 · M3 = 4 · P5 = 7 semitones

From C: E is a major 3rd (4 semitones), G a perfect 5th (7).

Practise this in the trainer — it opens with this lesson the first time the concept comes up.