Scale degrees — naming notes by function

Numbers, not letters

When a guitarist says “the 5”, they don’t mean the letter G or D — they mean the fifth degree of whatever key we’re in. In C major, the 5 is G. In E major, the 5 is B.

This is the single most useful mental switch you can make as a musician. Stop thinking in letter names. Start thinking in degrees.

The seven degrees of any major scale

Degree	Name	Function summary
1	Tonic	Home base; rest, finality
2	Supertonic	Mild motion, often passes
3	Mediant	Gives the major/minor character
4	Subdominant	Moves away from home; gentle pull
5	Dominant	Tension; wants to go to 1
6	Submediant	Relative minor’s home
7	Leading tone	Strong pull upward to 1

The traditional names (tonic, subdominant, dominant…) come from classical theory. You don’t have to memorise them, but they’re useful labels.

A worked example

Play “Twinkle Twinkle Little Star” in C major. The melody starts on the tonic (1=C), leaps to the dominant (5=G), then steps to the submediant (6=A) and back to the dominant (5=G):

Twinkle (1) twinkle (1) little (5) star (5) how I (6, 6) wonder (5)

That melody works in any key because the pattern of degrees — not the specific notes — is what makes it the song.

Roman numerals for chords

When we want to talk about chords by function, we use Roman numerals:

• Uppercase = major chord: I, IV, V
• Lowercase = minor chord: ii, iii, vi
• ° = diminished: vii°

The standard set in any major key:

I ii iii IV V vi vii°

Apply to C major:

C Dm Em F G Am B°

This is the harmonised major scale, the most important chord set in music. We’ll dive deep in Chord Progressions.

Why this matters

Suppose you learn “I-V-vi-IV” (the most common pop progression on Earth — used in “Don’t Stop Believin’”, “Let It Be”, thousands more):

• In C major: C G Am F
• In G major: G D Em C
• In D major: D A Bm G

Same pattern, three different keys. You haven’t learned three songs — you’ve learned a single transposable structure.

Try this

Take any song you know in C. Convert the chords to Roman numerals. Then play it in G major using those numerals. You’ve just transposed a song without a capo and without a chart.