How do you find the Roman numeral of a chord?

Find the key, count the chord’s root up the scale to get the number, then write it in capitals for a major chord and lowercase for a minor one. In C major, A minor is built on the sixth note and is minor, so it is vi.

Why are some Roman numerals lowercase?

Lowercase flags a chord with a minor third, and adding ° makes it diminished. In C major the lowercase ones are ii, iii, vi and vii°, whose third sits a minor third above the root.

What chords are I, IV and V in C major?

C, F and G major, built on the first, fourth and fifth notes. Together the three use all seven notes of the C major scale.

Roman Numerals in Music: How to Read I, IV and V

A Roman numeral names a chord by the scale degree it is built on: I is the chord on the first note of the key, V the chord on the fifth. A capital means major, lowercase means minor, in any key.

What does a Roman numeral name?

Number the notes of the scale 1 to 7 and build a triad on each one, using only notes of the key. The Roman numeral is the number of the note the chord starts on: I is the chord on the first note, IV the chord on the fourth, V the chord on the fifth. It says where the chord sits in the key, not which notes it contains.

The case of the numeral gives the quality. A capital letter is a major triad, a lowercase letter a minor one, and a small circle after a lowercase numeral marks a diminished one. In a major key the pattern never changes: major, minor, minor, major, major, minor, diminished. Minor keys have a pattern of their own (natural minor, with the raised seventh used only inside V and vii°): i, ii°, III, iv, V, VI, vii°. Of these i and iv are minor, III, V and VI major, ii° and vii° diminished.

The seven triads of C major with their numerals: I ii iii IV V vi vii°.

Numeral	Chord in C	Quality
I	C	major
ii	Dm	minor
iii	Em	minor
IV	F	major
V	G	major
vi	Am	minor
vii°	Bdim	diminished

How do you read I–IV–V–I in C and in A minor?

To read a string of numerals, find the note of the key that each number points to. In C major, I–IV–V–I is C, F, G, C. Move to G major and the numerals stay put while the letters follow the key: G, C, D, G. That portability is the whole reason for using numerals.

Minor keys use the same system with one catch. In A minor the main chords are i, iv and V: A minor, D minor and E major. The V is a capital because the seventh note of the scale is raised (G becomes G♯), which gives the chord the pull back to the tonic. That raised note is why V is major, where the natural minor scale would give a minor v, while i and iv stay lowercase. Leave the seventh natural and the chord on it is VII, a major chord (G–B–D in A minor); vii° is the diminished chord built on the raised note (G♯–B–D).

i–iv–V–i in A minor: A–C–E, D–F–A, E–G♯–B, A–C–E. The G♯ in the V chord is the raised seventh.

What do °, ø and the small numbers mean?

Mark	Means	Example in C
°	a diminished triad (with a seventh, a diminished seventh chord)	vii° = B–D–F
ø	a half-diminished seventh chord	viiø7 = B–D–F–A
7	a seventh added on top	V7 = G–B–D–F
⁶ ⁶₄	an inversion: which note is lowest	I⁶ = E–G–C / I⁶₄ = G–C–E

Small figures such as ⁶ and ⁶₄ are the same numbers a figured bass uses: they say which note of the chord is lowest. V7 and V⁷ are one chord, the raised figure being only a way of typesetting it. In a pop or jazz analysis a plain 6 after a numeral (I6) is a sixth chord, not an inversion; the small raised ⁶ of classical figures (I⁶) is the inversion.

How is a numeral different from a chord symbol?

A numeral names the degree a chord is built on, while a chord symbol names its notes outright. The reference has an entry on chord symbols, which sets the two side by side.