The 1-4-5 Chord System

A common way of talking about the use of guitar chords in pop songs is called Basic Chord Theory. It is also referred to as the “1-4-5” or (in Roman numerals) “I-IV-V”. Another term you will sometimes hear is the “Nashville System”.
I prefer the name “1-4-5” so that’s how I will refer to it here. And it is not so much a “theory” as it is a “system”.

Or another way of putting it is to say: “1-4-5 is a description of the ways chords tend to be used in pop songs.” Because the 1, 4, and 5 chords are the ones you will use most often when playing along with pop songs (including rock, country, blues, hip hop, etc.)

This makes 1-4-5 a shortcut to learning how to play along with songs. Just focus on the 1, 4, and 5 chords and you’ll often be at least 75% of the way home.

What is the 1-4-5 system?

Once you know what key you’re playing in, the chords you need will usually be the major chords based on the 1, 4, and 5 notes of the major scale of that key.

For example, the “1” note in the key of C is C. The “4” note is F. and the “5” note is G. It turns out that the major chords associated with these notes – C, F, and G – are the chords you will most often need to accompany a song in the key of C.

In the key of G the 1-4-5 chords are G, C and D.
In the key of D the 1-4-5 chords are D, G and A.
…and so on.

What this means for the beginning guitar player is that you can strum along with many songs just by learning a limited number of chords.

Of course there is more to the story – like for instance, minor chords – but we’ll get to that in the next post in this series.