What are the I, IV, and V Chords?
The I, IV, and V chords are the three most used chords in each major key. Aloud you would call them, “The one, four, and five chords.”
The I chord is built on the first note of the key. The IV chord is built on the fourth note of the key. And, the V chord is built on the fifth note of the key.
For example, the key of C major is spelled C, D, E, F, G, A, and B. The first note is C, the fourth note is F, and the fifth is G. The I, IV, and V chords in the key of C are a C major triad, an F major triad, and a G major triad. We’d simply say, “The chords are C, F, and G.”
You should notice the notes of each triad fit within the key. Remember, that’s what diatonic means within the key. C major is made up of the notes C, E, and G. F major is F, A, and C. And, G major is G, B, and D. The key is what binds the chords together into a small family.
I, IV, and V Everywhere You Look
As I said, these three chords get used more than any other chords in a key. In music theory we call them the primary triads or primary chords. That should give you any indication of their importance.
Hundreds of thousands of songs revolve around these 3 chords. Many songs only use these chords. And, even more use the I, IV, and V plus one or two other chords.
Songs have used the primary chords for centuries. It doesn’t matter if it’s J.S. Bach or The Ramones. Everyone uses the I, IV, and V chords. If you pay attention to it, you'll recognize it and music will get a little easier to comprehend.
The Same in Every Key
The I, IV, and V chords work the exact same way in every key. You can build the three basic major triads of each major key on the first, fourth, and fifth notes of the key.
For instance, in D Major (D, E, F#, G, A, B, C#) the chords would be D, G, and A. In Ab Major (Ab, Bb, C, Db, Eb, F, G) they’d be Ab, Db, and Eb.
The I, IV, and V are Unique
Every key has its own unique set of I, IV, and V chords. No two keys share the same set. Because of this uniqueness when we hear these three chords used in a piece of music, our ear gets a sense of the key of the music, or its tonality.
Giving the listener a sense of tonality is important for creating effective music. We’ll dive into this more advanced topic later. But, as a preview, I think music’s essential ingredient is to take the listener somewhere. To do this we need to give the listener a sense of where “home” is. When using the I, IV, and V chords together, your ear perceives I as home. Once home is established we can then take the listener away from home and back to home. Without a home, music will simply wander.
The I, IV, and V Chords on the Fretboard
The I, IV, and V chords appear all over the fretboard. The better you learn your keys, chord patterns, and the notes of the fretboard, the more access you’ll have to finding each key’s I, IV, and V, and the more you'll be able to do with them.
At first most people recognize the pattern of root notes for each chord from the one octave major scale pattern. For example, in the key of C, the roots are C, F, and G.
Then you could build a major triad on each of those roots.
As you advance you will start to see other ways of playing and locating the I, IV, and V chords on the fretboard. You might see it moving to a lower IV chord root and lower V chord root note. Then building a major triad off of each root.
Or, you might see it moving to a higher IV chord root and a lower V chord root.
There are numerous possibilities.
I, IV, and V Chords in Each Key
Here is a table of the I, IV, and V chords in all 15 major keys. Don’t kill yourself trying to memorize these all in one shot. With time and experience you will eventually memorize these groups of chords. You're going to encounter them so much that you’ll come to see and hear them as a small family.