I've been taking a fairly beginner music expression course and I've recently learned about chord progressions using chords in I, IV, V.

However, I'm aware that most popular music that you would hear on the radio is generally a four-chord song. How is the fourth chord generally determined?

  • Note that the first three chords are not always I, IV, and V. Smells Like Teen Spirit is i - iv - III - VI (major/minor flavors implied as the actual chords have no thirds). Dec 4 '15 at 19:23

Adding a fourth chord to a three chord progression consisting of the I - IV and V chords in a major key can serve many purposes.

For one, it can create a more dynamic and more interesting chord progression. A ii (two minor) or iii (three minor) or vi (sixth minor) chord can add tension to the progression which will beg for resolution back to the root or tonic chord - thereby creating a push pull effect of tension and resolution. A minor chord in a major key progression can serve to lead you to one of the other major chords or serve as a pivot point to switch the order of the progression. These are just some examples of how one of the minor chords can be used in a four chord progression in a major key.

Many possible 4th chords are available including the ii, iii, or vi. You can also use a diminished 7th degree chord or even a flattened 7th degree major chord. Extensions can also be used (7th, 9th, augmented, suspended).

One very commonly used fourth chord in a four chord progression is the vi chord and a popular progression is the I-V-vi-IV progression. Some of the reasons the iv chord is often used as the fourth chord can be found in the answers to this question Why is the I-V-vi-IV chord progression so popular

Ultimately the fourth chord you use depends on what purpose you want it to serve in your song and what you want to accomplish by using it.

A comprehensive online search may yield some helpful guides such as the charts pictured below. As a disclaimer, these charts are merely examples of devices that have been invented to simplify the process of choosing chords and don't purport to offer every possible solution and should not be treated as rules that cannot be broken. Ultimately your goal should be to develop the ability to effectively use your own creativity (guided by music and chord theory) to compose chord progressions that help you express your own personal musical ideas.

Chords for Major Keys

Chord Ladder

Chord Progression Map

  • If a song begins on an upbeat it is likely that the progression will start on the dominant.
    – Neil Meyer
    Nov 30 '15 at 9:00
  • Arguably the most used 4 chord sequence is I- vi- IV- V. There must be hundreds if not thousands.
    – Tim
    Nov 30 '15 at 18:05
  • @NeilMeyer - if the song begins on the upbeat, it's an anacrucis, and the actual progression starts on the tonic, which is the norm.
    – Tim
    Nov 30 '15 at 18:06
  • 1
    @RockinCowboy - With due respect, your pictures / graphs are quite silly; the tension -> resolution ladder is quite incorrect: there is no way a "iii" chord is to be considered a "tense" chord. In your chord progression graph, it illustrates that IV cannot go to "vi", which is insane, since that movement offers incredibly smooth voice-leading and is actually very common to hear in music. It doesn't show how "ii" can substitute IV or how "vi" can substitute I, and omits the seven-diminished chord entirely. Apart from showing some major scales, the matrix you provide seems to be incoherent. Dec 1 '15 at 23:43
  • 1
    @jjmusicnotes I did not create the charts, I found them & although the ideas suggested are not cast in stone, I personally find them useful. I agree that a IV can go to a vi so the word "rules" in the instructions should be "suggestions". If you follow the "suggestions", you will have a chord progression that works. But you could certainly deviate from the suggestions and still have a chord progression that works. The OP is a beginner so just offering some cheat sheets. The charts are designed to be simple & not cover every possibility. I personally feel a iii chord creates tension. Dec 2 '15 at 0:01

Not necessarily so. There is an awful lot of 3 chord songs (and a lot of awful 3 chord songs, but that's just a joke) that work very well. If a fourth chord is deemed needed, it will usually be one of the following. A minor belonging to the same key, as in ii, iii or vi. The vi is probably the most prevalent of these. Followed by ii then iii. But it will depend on the song. Any extra chord will have to match the notes in the melody. That's just what any chord does. The next option is the dominant chord which leads to the dominant of the key - II. Thus, in C, the missing chord , apart from C, F and G, would be either Am, Dm, or Em, or D(7).

Other options in general use could include I7, to move to IV, and iv (minor F in C) to get back to I. There's maybe a list of probable chords, in usage order, to consult. In fact, it may be an interesting exercise to compile such a list from popular song chord make ups that does this. It'd probably go I, V, IV, vi...

  • 1
    To clean up some of your points concerning music theory - the dominant of a key is the V chord, not a II, which would be a V/V a.k.a a secondary dominant. You would never label a "I" chord as a "I7", but rather a V7/IV - you need to show functional relationship when present. You're correct on both counts about three-chord songs, but you miss the mark in answering the OP's question. In a four-chord progression, the last chord is very, very typically going to be a IV, V, or secondary dominant. Use of a "vi" or "ii" typically serve as substitutions of I, IV, and V to prolong the middle. Nov 29 '15 at 21:41
  • @jjmusicnotes - thank you for the guidance, much appreciated.What I tried to portray was the dominant chord leading to the dominant of the key. Thus, in C maj., (dominant G), it would be D (or D7). If I call a chord V7/IV, then yes, it's the dominant 7th leading to the subdominant, which is where most dominants go - up a fourth. My glitch is if I see V7/IV, and I'm reading it live, I see the V7 first, and automatically go to D7 in C. II may not be technically correct, but it helps me play the right thing! The 'fourth chord' (O.P.) I took to mean the next most used chord after I, IV and V.
    – Tim
    Nov 30 '15 at 9:02
  • @jjmusicnotes - where does that leave Sweet Georgia Brown? In G, goes E - A - D - G chordally. So given G=I, that could make E technically V/V/V - rather unwieldy. And the B7 in there would be V/V/V/V. Help!
    – Tim
    Nov 30 '15 at 9:05
  • Thanks for explaining how you interpreted the OP's question about the "fourth chord", I obviously took it to mean the fourth chord of a sequence. Regarding Sweet Georgia Brown, if the chords are functioning as secondary dominants, then yes, V/V/V or V/V/V/V would be absolutely right, even if it seems silly / stupid. I've analyzed Beethoven string quartets that had a similar train of secondary leading-tone chords, as well as non-functional secondary dominants (such a rebel!). Yes, you'll feel stupid writing that many "V's", but it's correct. :) Nov 30 '15 at 23:44
  • @jjmusicnotes - thanks again. Some of these rules were made by non-musos, I guess! Incidentally, in my first comment, I should have said 'In C, if I see V7/IV, I automatically go to G7, not D7. A sort of N.N.S. I prefer and have adapted.
    – Tim
    Dec 1 '15 at 8:13

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