Roman numeral chord progressions: the guitarist's guide to I-V-vi-IV, ii-V-I and the blues

Most songs you want to play use the same handful of chord progressions. "Let It Be", "With or Without You" and "No Woman, No Cry" are, harmonically, the same four chords in different keys. Guitarists who know this learn songs faster and transpose on the spot.

The tool that makes it possible is Roman numeral notation: instead of naming chords (C, G, Am, F), you name their position in the key (I, V, vi, IV). This guide gives you the diatonic chords in the five most common guitar keys, the progressions that power popular music, a method for transposing with or without a capo, and a step-by-step way to analyse any song.

In short: a Roman numeral tells you which degree of the key a chord is built on. Uppercase means major (I, IV, V), lowercase means minor (ii, iii, vi), and ° means diminished (vii°). In a major key the pattern is always I ii iii IV V vi vii°. Learn I-V-vi-IV, I-IV-V, ii-V-I, vi-IV-I-V and the 12-bar blues as numbers, and you can play them in any key.

What are Roman numeral chord progressions?

A chord progression is a sequence of chords. Writing it in Roman numerals means describing each chord by the scale degree its root sits on. In the key of C major, C is degree 1, D is degree 2, E is degree 3, and so on up to B, degree 7. A G chord in C is therefore "V", because G is the fifth note of the C major scale.

This is called Roman numeral analysis, and it has one huge advantage: the numbers do not change when the key changes. C G Am F in C major and G D Em C in G major are both I-V-vi-IV. Learn the pattern once and you own it in all twelve keys.

The conventions are simple:

• Uppercase (I, IV, V): major chord.
• Lowercase (ii, iii, vi): minor chord.
• Lowercase with ° (vii°): diminished chord.
• A 7 after the numeral (V7, ii7, Imaj7): a seventh chord. V7 is a dominant seventh, such as G7 in C.
• A ♭ or ♯ before the numeral (♭VII, ♭VI): a chord built on an altered degree, usually borrowed from the parallel minor.

The diatonic chords in major keys

Stack thirds on each note of the major scale using only notes from that scale and you get seven diatonic chords. The quality pattern never changes: major, minor, minor, major, major, minor, diminished.

Here are the five keys guitarists use most, because they sit on open strings:

Key	I	ii	iii	IV	V	vi	vii°
C major	C	Dm	Em	F	G	Am	Bdim
G major	G	Am	Bm	C	D	Em	F#dim
D major	D	Em	F#m	G	A	Bm	C#dim
A major	A	Bm	C#m	D	E	F#m	G#dim
E major	E	F#m	G#m	A	B	C#m	D#dim

Read the table vertically and you see the point: the V column (G, D, A, E, B) is always a major chord a perfect fifth above the I. On the guitar, with a root on the 6th string, the IV root sits on the 5th string at the same fret and the V root on the 5th string two frets higher: G at the 3rd fret, C at the 3rd fret, D at the 5th fret.

In pop, rock and folk, I, IV, V and vi do most of the work. The vii° is rare outside jazz and classical music.

The degrees have jobs

Each degree has a function. The I is the tonic: home, rest. The V is the dominant: tension that wants to go home. The IV is the subdominant: movement away from home. The ii often stands in for IV, and the vi often stands in for I (they share two notes).

The diatonic chords in minor keys

Every major key has a relative minor that uses the same notes, starting on degree 6. A minor is the relative minor of C major, so its chords are the same seven chords seen from a different home: Am, Bdim, C, Dm, Em, F, G.

In the natural minor scale, the pattern is i ii° III iv v VI VII:

Minor key	i	ii°	III	iv	v	VI	VII
A minor	Am	Bdim	C	Dm	Em	F	G
E minor	Em	F#dim	G	Am	Bm	C	D
B minor	Bm	C#dim	D	Em	F#m	G	A

One practical detail: in most minor-key songs, the v chord is turned into a major V (E or E7 in A minor) to create a stronger pull back to the i. That raised note (G# in A minor) comes from the harmonic minor scale. So if you see Am Dm E7 Am, it is i-iv-V7-i, not a mistake.

The progressions that power popular music

I-V-vi-IV and its rotations

The I-V-vi-IV progression is the backbone of modern pop. Start on any of its four chords and loop it, and you get a "rotation" with a different mood.

Rotation	Numerals	In C	In G	Heard in
Original	I-V-vi-IV	C G Am F	G D Em C	"Let It Be", "No Woman, No Cry"
Minor start	vi-IV-I-V	Am F C G	Em C G D	"Zombie" (The Cranberries)
From IV	IV-I-V-vi	F C G Am	C G D Em	Many modern pop choruses
From V	V-vi-IV-I	G Am F C	D Em C G	Bridges and pre-choruses

Exercise: play G D Em C with four down-strums per chord at 80 BPM, then start the loop on Em without changing anything else. Same chords, but the song now sounds sadder because your ear hears Em as home.

vi-IV-I-V: the "sad" rotation

vi-IV-I-V deserves its own mention because it is so common in ballads and anthems. Is it in the major key starting on vi, or in the relative minor (i-VI-III-VII)? Both readings are correct. The chord the song settles on decides the key: if the song ends and rests on Em, call it E minor (i-VI-III-VII); if it rests on G, call it G major (vi-IV-I-V).

I-IV-V: rock and roll in three chords

I-IV-V is the oldest engine in rock, country and folk. "La Bamba" (C F G), "Twist and Shout" (D G A) and "Wild Thing" (A D E) all run on it. In A, play A, D and E as open chords: they share the open A and E strings, which is why the key of A rings so well on guitar. Try the variant I-IV-I-V (A D A E) and end on I to hear the full cadence.

ii-V-I: the jazz cadence

The ii-V-I progression is the central move of jazz: Dm7 G7 Cmaj7 in C, Am7 D7 Gmaj7 in G. The roots move by fourths, and the guide tones (third and seventh) move by a semitone or stay put: the C of Dm7 falls to B, the third of G7, while F stays and becomes G7's seventh, then falls to E, the third of Cmaj7. Standards such as "Autumn Leaves" are built almost entirely from chains of ii-V-I in major and minor (in minor: iiø7-V7-i, for example Bm7♭5 E7 Am).

Play it with barre shapes: Dm7 at the 5th fret (5th-string root), G7 at the 3rd fret (6th-string root), Cmaj7 at the 3rd fret (5th-string root). Your hand barely moves.

The 12-bar blues

The 12-bar blues uses only I, IV and V, almost always as dominant seventh chords. Here it is in A, one chord per bar:

Bars 1 to 4	Bars 5 to 8	Bars 9 to 12
I7 I7 I7 I7	IV7 IV7 I7 I7	V7 IV7 I7 V7
A7 A7 A7 A7	D7 D7 A7 A7	E7 D7 A7 E7

The "quick change" variant puts IV7 in bar 2 (A7 D7 A7 A7). The last bar (V7) is the turnaround that sends you back to the top. Play it with a shuffle feel at 90 BPM, and in E (E7 A7 B7) once you are comfortable in A.

How to transpose any song by thinking in numbers

Transposing is a three-step job once you think in numbers:

1. Find the key and write the progression as numerals. Example: E B C#m A in E major is I-V-vi-IV.
2. Pick the new key, often to suit a singer or to get open chords.
3. Read the numerals in the new key using the table above. I-V-vi-IV in G is G D Em C.

No counting semitones chord by chord: the quality (uppercase or lowercase) travels with the numeral. The interactive circle of fifths shows the diatonic chords of every key on one screen, which makes step 3 instant. For more on the keys themselves, read the circle of fifths for guitarists.

Transposing with a capo

A capo lets you keep familiar open shapes and change the key. Each fret raises everything by one semitone. The rule: capo fret = number of semitones from the shape key up to the sounding key.

Shapes you play	Capo 1	Capo 2	Capo 3	Capo 4	Capo 5
G (G D Em C)	A♭	A	B♭	B	C
C (C G Am F)	D♭	D	E♭	E	F
D (D A Bm G)	E♭	E	F	F#	G

Example: a song is in A, but you want to strum G-shape chords. G to A is two semitones, so capo at the 2nd fret and play G D Em C. The numerals (I-V-vi-IV) stay the same, only the sounding key moves. The capo transposer in the guitar toolbox does this calculation for any pair of keys.

Analysing a song step by step

Let us analyse a famous four-chord loop: G B C Cm (the verse of "Creep" by Radiohead).

1. List the chords: G, B, C, Cm.
2. Find the home chord: the loop starts and resolves on G. Hypothesis: G major.
3. Number the diatonic chords: G is I, C is IV. These fit G major.
4. Flag the outsiders: B major is not diatonic in G (the diatonic chord is Bm, iii). B is the V of Em, so it is a secondary dominant, written V/vi or III. Cm is not diatonic either: it is iv, borrowed from G minor, a classic case of modal interchange.
5. Write the result: I-III-IV-iv. The two outsiders explain the song's colour: a bright, unexpected B, then the dark Cm sliding back to G.

Use the same five steps on any song. If you want a second opinion, the AI progression analysis returns the key and a Roman numeral reading you can check against yours, and our guide to AI chord progression analysis explains how to judge its suggestions.

A 10-minute daily practice routine

• 2 minutes: say and play the diatonic chords of one key from the table (I to vi), changing key every day.
• 3 minutes: play I-V-vi-IV and vi-IV-I-V in that key, four strums per chord, with a metronome.
• 3 minutes: play one 12-bar blues chorus in that key, or the closest key with good open chords.
• 2 minutes: take a song you know, write it in numerals, then play it in another key.