Basics – How to Harmonise a Melody Using Primary Chords

How can I harmonise my melody?

You can harmonise any melody using just three chords.

Really? Great! Which three?

I, IV and V.

Erm… no, you’ve made a mistake, chords have letter names: A, C, F, G…

They do, but they can also be given numbers. Roman numerals are used to generalise.  Every major scale is different, but they all have the same structure, so they have the same kind of chords. Chord I is always a major, chord IV is a fourth up and major, chord V is a fifth up and major.

For example: in C major the three chords are C, (made up of CEG), F (FAC) and G (GBD).

The notes in this scale are C D E F G A B C. Every single note of the scale can be found in those three chords CEG, FAC, GBD.

But how does that help me add chords to a melody?

Okay, let’s take a look at a well known melody:

Oh when the saints, go marching in

C     E     F     G          C    E       F    G

Oh when the saints go marching in

C     E       F    G        E     C    E      D

Here’s just the melody: Download

If you have a good enough ear, you’ll be able to hear that most of those two lines fit with one chord. If you know enough about music theory you’ll be able to see that the vast majority of the notes used are from the C major chord: C, E and G.

The only notes that don’t fit with that chord are the Fs and the D at the end. Now the Fs don’t happen on important words, they fit with the word ‘the’ and because they fall on weak beats, we can pretty much discount them when choosing our chords.

The D on the other hand isn’t in in our C chord, and it falls on a strong beat, the first beat of a bar. Therefore we need to change. Which primary chord has a D in it? G major (GBD).

Here’s the melody with those chords added:Download

In the next post we’ll take a look at how to find chords for the rest of ‘Oh When the Saints’.