Understanding chord numbers will help you change keys
You will sometimes hear musicians using numbers to denote chords. They’ll use terms like a fourth or fifth chord.
This is not as complicated as it sounds at first and is worth exploring because it will help you to understand the relationship between chords and enable you to transpose songs from one key to another quite easily.
Take a look at this first line of our chart showing the main chords used in the key of C Major.
The numbers at the top of the chart refer to the numbers commonly used to denote the chord below.
The first number (1) refers to the root or key chord, that is the chord with the same name as the key itself. In the case of C Major, the first or root chord is C. In the key of D Major, the first or root chord is D and so on.
Songs usually begin on the root chord and they always finish on it.
Once you’ve established the root chord, the rest just follow in alphabetical order. So, as we see on the chart, in the key of C Major, C is the first chord, Dm is the second and so on.
Harmonising any song with three chords
You may have heard how it’s possible to harmonise any song with just three chords.
The three chords that can do this are always the first, the fourth and the fifth chords no matter what the key.
So, if you look at the chart, you will see that for the key of C Major, the first chord is C, the fourth is F and the fifth is G or G7. In the key of D Major, that becomes D, G and A(A7) and so on.
The multi-purpose first, fourth and fifth
It’s worth making sure you understand this fully and learn what chords 1, 4 and 5 are in every important key. They will enable you to transpose keys at will without referring to any charts at all.
These three chords will be used in virtually in every song you ever play whether Irish folk music, pop, rock and roll, country and western or whatever.
They are also the three chords used in 12-bar blues.
The next most important chords
Not all chords are created equal. The first, the fourth and the fifth are the ones most frequently used.
The next most used chord is the minor sixth. As you will see from the chart, in the key of C Major, the minor sixth is Am.
The minor second and the minor third also pop up quite often.
Some songs, of course, will use chords not shown here but we’ve tried to keep the chart as simple as possible so it is easy to understand and use. The six chords listed will cover the vast majority of songs you come across.
Once you get used to working with it, you will get the idea and work out how to transpose the occasional unusual chords yourself. If not, let us know and we’ll add a more extensive chart.
Changing key can easily become second nature
Try to learn the main chords in the five most important keys and see how thinking about them in terms of being root chords, fourths, fifths, minor sixths etc enables you to transpose keys quite easily.
You’ll be surprised how it quickly it becomes second nature to you.
This, of course, is a very simple approach to the subject but it is accurate and highly practical.
We hope it will help beginners and even the more experienced to play songs in keys that best suit them.
Explore the use of the capo
No matter how good you get at playing in the five prominent keys, you should still explore the advantages of using a capo.
Click on the links below for more on using the capo and transposing keys.
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