Theory Basics: What is I-IV-V anyway?

Understanding some simple musical concepts can go a long way for a guitarist. From playing at open jams, to playing with a non-guitarist, to learning songs quickly, there are a few terms and ideas that allow a musician to quickly communicate ideas. While much of today’s guitar music is riff and pattern-based (those darn kids!), older styles of music are more chord/harmony based, and this series will decode some of the strange terms these old-timers use. Playing with musicians with diverse backgrounds is a quick way to measure our skill and advance outside of our comfort zone. This article will explain what a musician means when he/she calls something a I-IV-V progression, and allow you to navigate the world of the most common chord progression.

Key to the Highway

This guy is thinking about this too much.
This guy is thinking about this too much.

In western music (most music of the Western hemisphere), chords and notes are arranged in things called keys. There are 12 keys in our musical system, and each of those keys has 7 notes, and 7 basic chords. The guitar, unlike an instrument like the dulcimer or folk harp, is capable of playing in all 12 keys. Yes, I know, there are certain ‘guitar keys’ that are more common than others, but, as much as we hate to admit it, it isn’t all about us. Composers freely compose in all keys, and to make matters worse, sometimes borrow notes and chords from other keys. Here, we will stick to one key at a time- I want us to understand what is going on.
Take the key of C, or The White Keys on the Piano. The notes in the key of C are: C D E F G A B. If we read my article about how to derive chords in any key, we can come up with 7 basic triads: C, Dm, Em, F, G, Am, Bdim. In music, we give these chords Roman numerals:

  • C or I
  • Dm or ii
  • Em or iii
  • F or IV
  • G or V
  • Am or iv
  • Bdim or vii

Notice that some use capitals and some do not. It makes it easy to remember that the I, IV, and V are related to major chords, while the ii, iii, & vii are related to minor chords. Ideally, you should know the I, IV, V in every key, or at least in the friendly guitar keys of A, C, D, E, & G.
You can also extend these chords to 4-note 7th chords and beyond. It is also perfectly fine to combine the more complex-sounding four-note chords with the more basic three-note chords above.

Three of a Perfect Pair

The three chords above that we are concerned about above are C, F, and G. These three chords have a pretty special relationship, and have been used as the basis of millions of songs over the years, from folk music of the 1800s to much of Led Zeppelin’s early work. This also includes most classic country, all blues, and much of jazz as well. So, we are starting to see the implications from knowing the three most popular chords in any key!

I have no idea what this woman is doing.
I have no idea what this woman is doing.

However, even though we now know the right chords, we still don’t know the right order of the chords. We don’t know the tempo, strumming pattern, or the overall feel of the song either. These components are what keeps songs using a I-IV-V progression from sounding all alike. It is also what separates our renegade guitar playin’ from that uppity classical music: you gotta use your ears and intuition. It would seem logical that the chords are in the order we say them: I-IV-V, and in some cases they are. But in many (most) cases, they aren’t. So you have to listen. Generally speaking, the song always starts with the I, then moves to the IV. The V chord is used to provide tension which usually resolves back to the I. Once you start listening for the chords, you will hear it.

I Don’t Hear It

That’s ok, it took me awhile to hear it too. Here is a folk-type progression in the key of C. My only change is that I substituted a G7 for the G as the V chord, as it allows you to hear the differences between them all. I kept the I-IV-V chords in order, so when you hear the V chord (G7) you can hear it resolve back to the I (C).

Country music has benefited from the I-IV-V as well, although here, the overall ‘feel’ is different, and I am not playing the chords in order. I am starting and ending with the I, and those same tensions and resolutions are there. We still call it a I-IV-V progression though, because those are the only chords I am using. This is a really bluegrass-y, traditional country approach.

The Seymour Duncan Jazz pickup was used for all examples.
The Seymour Duncan Jazz pickup was used for all examples.

Blues is a different animal. In blues, you still use the same three chords, but stylistically, these are (usually) changed to dominant 7th chords. So, C becomes C7, F becomes F7, and G becomes G7. This gives it the characteristic blues sound, and again, this is still called a I-IV-V, even though the chords are not in that order. They are still the only chords we use, though- and, like the other examples above, the song just repeats the same progression over and over. So you really just have to know about 20 seconds of chords to get through the whole song.

Three Chords and the Truth

He changed the world with 3 chords. Your turn.
He changed the world with 3 chords…now it is your turn.

Knowing the I-IV-V in any key allows instant transposition as well. If the song you normally play in C uses a I-IV-V progression, yet you now need to raise the pitch for a different singer, the relationship of the chords to each other remains constant: you just plug in the new chords. Here is a list of the most common ‘guitar keys’ and the I-IV-V chords in each key:
A: A, D, E
C: C, F, G
D: D, G, A
E: E, A, B
G: G, C, D

If you ever have to play with horn players, it is good to know these as well:
Bb: Bb, Eb, F
Eb: Eb, Ab, Bb
A good chord book or app is essential. Even accomplished players know relatively few chords compared to a good keyboardist. From 60’s pop tunes, to Sweet Home Alabama, to Livin’ After Midnight, the I-IV-V has been used countless times.

Do you have a favorite song that uses the I-IV-V progression? What chord progressions have you been working on?

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6 Comments

  1. please post more about other progressions or “song structures.” I really enjoyed this article!

  2. Cool article! A correction: In the Roman Numerals section you misprinted the Am as a iv chord, not the correct vi. And then you left it out in the following descriptive paragraph.

  3. You mentione Am = iv in the key of C, instead it should be vi
    Roman numerals:
    C or I
    Dm or ii
    Em or iii
    F or IV
    G or V
    Am or iv
    Bdim or vii

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