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what is I-IV-V chord progression

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Active Member
Joined: 20 years ago
Posts: 3
Topic starter  

I have been playing for a few months now and keep seeing I-IV-V chord progression popping up - what is it guys I'm confused?


Illustrious Member
Joined: 22 years ago
Posts: 5108

It's the first, fourth, and fifth chord of a progression and the basic formula for the twelve bar blues.

Read David's lesson on Before You Accuse Me. It's an excellent explanation of the I IV V formula.

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-- John Lennon

Eminent Member
Joined: 20 years ago
Posts: 35

Example in the key of A

A Major Scale: A,B,C#,D,E,F#,G#,A
I chord would be an A chord
II chord would be a B chord
III chord would be a C# chord
IV chord would be a D chord
V chord would be an E chord
VI chord would be F# chord
VII chord would be G# chord

I,IV,V would be an A,D,E chord progression
I,IV,V7 would be an A,D,E7 chord progression
I,ii,IV,V would be an A,Bm,D,E (lower case Roman numerals imply minor)

Reputable Member
Joined: 20 years ago
Posts: 243

To expand on what Markminni said, in each key you have a standard seven chord progression. Find the scale for the key, then you get this pattern:

I - ii - iii - IV - V - vi - VIIdim

So in the key of C, the scale is:


and the chords are:

C maj - D minor - E minor - F maj - G maj - A minor - B diminished
which are the I-ii-iii-IV-V-vi-VIIDim chords respectively.

So, I-IV-V would be C-F-G

This works for any key, with the notes in the scale giving rise to the chord in the progression.

Blame it on the lies that killed us, blame it on the truth that ran us down.

Illustrious Member
Joined: 22 years ago
Posts: 5108

Be sure you know how to build a scale as well.
The chord progression follows the notes of the scale. Markminni gave you the scale for A (key of A).
This article --Theory without Tears explains the basics of key and scale if you need that info too.

Well we all shine on--like the moon and the stars and the sun.
-- John Lennon

Active Member
Joined: 20 years ago
Posts: 3
Topic starter  

thanks guys - great info, things are becoming clear :D

Honorable Member
Joined: 22 years ago
Posts: 646

There are 12 notes in the equal tempered instruments everybody uses these days, hence 12 keys. Each key uses 7 out of those 12 notes. Here are the notes for the different keys:

Key Minor Signature 1 2 3 4 5 6 7
C major A minor C D E F G A B
G major E minor # G A B C D E F#
D major B minor ## D E F# G A B C#
A major F# minor ### A B C# D E F# G#
E major C# minor #### E F# G# A B C# D#
B major G# minor ##### B C# D# E F# G# A#
F# major D# minor ###### F# G# A# B C# D# E#
F major D minor b F G A Bb C D E
Bb major G minor bb Bb C D Eb F G A
Eb major C minor bbb Eb F G Ab Bb C D
Ab major F minor bbbb Ab Bb C Db Eb F G
Db major Bb minor bbbbb Db Eb F Gb Ab Bb C
Gb major Eb minor bbbbbb Gb Ab Bb Cb Db Eb F

Now, building chords from those notes, is known as "harmonising the scale and is done by picking every other note from the scale (note that 9=2, 10=3, 11=4 and 13=6):

Degrees of notes C major scale notes
1 2 3 4 5 6 7 8 C D E F G A B C Chord no. Chord name.
1 3 5 C E G I C major
2 4 6 D F A ii D minor
3 5 7 E G B iii E minor
4 6 8 F A C IV F major
5 7 9 G B D V G major
6 8 10 A C E vi A minor
7 9 11 B D F vii° B diminished

Thus the primary chords of each key, the I, IV and V are major and the secondary chords, the ii, iii and vi, are minor. The diminished chord, the vii°, can be thought of as a substitute for the V7 (5-7-9-11) and they function the same.

Minor keys are a little more complicated. In Aeolian mode or natural minor (1-2-b3-4-5-b6-b7-8), the i, iv and v are minor. In practice, that sounds very sedate and undramatic, so in practice people usually use a major or dominant V or or V7. This gives rise to the harmonic (1-2-b3-4-5-b6-7-8), and melodic (1-2-b3-4-5-6-7-8), minor scales.

Helgi Briem
hbriem AT gmail DOT com