The chord and key of A Major (and how to use it in your songs).

It’s one of the most common chords in modern music and the root key of many smash-hit songs. Learn how to use the chord and key of A Major with our guide!

A Maj Hero

The basic triad looks like this:

A Maj triad
Chord Root Third Fifth
A Major A C# E

And sounds like this:

You can add notes, or ‘complexity’ to this triad and increase the polyphony. These additional notes are called ‘chord tones’. We already have the Root, third and fifth present in the basic triad.

Creation of the triad:

A Maj & C#

Starting from the root, triad chords contain 2 additional chord tones. The number of semitones between each note varies if the chord is Major or Minor. In A Major, the middle note is 5 semitones above the root. We call this note the ‘third’ because it is three whole notes from the root, A. On a piano, a semi-tone step is simply a key up or down from the current key. So, we can count five keys (or 3 whole notes) up from C to reach the third – C.

The middle note, or third, is what signifies whether a chord is Major or Minor. The 1st and 5th notes are the over-arching chord tones. Regardless of scale, the 1st and 5th together always signify which chord is being played.

In this case, it’s A and E:

A & E

Pro Tip

When playing from one chord to the next, we at Captain Plugins generally try and minimize the leap for a pianist. That means, we try and keep the distances between notes from chord to chord as low as possible – like how a pianist would probably play it.

With 12 notes in a chord, chord tones more than five semitones away can often be accessed with a smaller leap by going down in the scale from the root. That means the pianist’s hand is less stretched when playing a chord progression.

A Maj full complexity

Adding more chord tones to the chord of A Major is simply about repeating the triad notes in a higher or lower octave.

In Captain Chords, you can generate the chord of A Major at the touch of a button. You can add complexity too, and even play A (and all the chords in its scale) with one finger!

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Relative Minor

Every Major chord has a relative Minor chord that complements it. If you’ve ever seen the Mixed in Key Harmonic Mixing Wheel (AKA the ‘Camelot’ Wheel) you’ll be familiar with the way chords ‘connect’ based on their position on the wheel.


The outer ring has the Major chords, the inner ring has Minors. Look at the lower left side of the wheel. 11B = A Major, and is positioned next to 11A = F Sharp Minor. These are ‘relative’ keys – very useful when writing chord progressions as you know the chords in the scale will sound ‘correct’ even when played on top of one another.

A Major Inversions

Remember that an octave is made up of 12 semitones? In the chord of A, the fifth is E. E is 7 semitones up from A, and therefore 5 semitones down from it, too. The lower E is one whole octave below the higher one.

Do you see that this is an example of the same chord with one note played in a different octave? This is a ‘version’ of the root chord – or, as we call it in music theory, an ‘Inversion’. You can choose which ‘version’ of the chord to play. It can seem a bit confusing, at first, but it’s super useful when you get your head around it!

Inversions of A Maj

As discussed earlier, ‘inversions’ are ways of playing the same chord but with one or more of the same notes played in a different octave. This has the effect of changing which note is at the root of the chord. For this reason, we call it a ‘voicing’. In the image above, we can see the default triad, 1st inversion and 2nd inversion. The ‘voice leading’ each respective chord is A, C#, and E. Perhaps this is easier to understand in a simple chart:

Chord Root Third Fifth
Default Triad A C# E
1st inversion C# E A
2nd inversion E A C#

A Major (1st Inversion):

A Major (2nd Inversion):

Try playng the inversions together with the root – the voicings create quite different textures. Each may also transition more smoothly between other chords in your progressions, without changing the pitch of your A chord:

A Major Suspended chords.

Suspended chords AKA ‘sus chords’ are simply regular triads in which the middle note – the third – is moved. If it’s moved down one whole note, it’s a Suspended 2nd, and if it’s moved up one whole note, it’s a Suspended 4th. Each adds a profoundly different character to the sound of the chord.

sus chords

A Major Suspended chords. Sus2 on the left, sus4 to the right.

Here are the two suspended chords of A Major played together (starting with the default A chord for comparison):

7th chords.

A Maj7 & A7

AMaj 7 (left) / A7 (right).

Before we move onto the key of A Major and how to work in it, a final word on 7th chords. There are four types of 7th chord: Major, Dominant, Half-Diminished, and Diminished. They’re called 7ths, because each one adds a note that is 7 notes from the root. For example, you can make a A Major triad into a A 7th (Dominant) by adding the note 7 notes above A to the Chord. The A 7th (Dominant) interval is equal to 7 whole notes, which in A is G.

There are three other types of 7th chord, created by either using a whole or flat 7th note, or a major, minor or diminished root triad. Dominant 7ths of a minor chord, for example, use a flat 7th, while Major 7ths use the whole 7th note. This would be reversed if we were looking at a Major chord. It does get a little complex, but can be well worth learning as 7ths can give your chord progressions wonderful texture. For more information on this, check out our article on composing with 7th chords!

Other Flavors of A Major.

You can continue adding notes to the chord of A. Many musicians call these new chord types ‘flavors’, or the adding of ‘Extensions’. Ultimately, these flavors occur when you add notes outside the ‘triad’ chord tones.

For example, a A9 chord is an A 7th chord with another note added, 2 notes up from the 7th in the A Major scale. So, it’s a A7(Dom) with an additional B.

7th chords, and other extensions like 6ths, 9ths and so on, are useful for two main reasons. One, they add an additional tone to the chord, affecting its character. Secondly, this extra tone can help bridge the gap between chords, by smoothing out the distance between each chord. For example, look at this chord progression:

7ths bridging

The chord progression goes A – C#m – F#m7 – D. The F#m7th in this progression shares an extra note with the preceding C#m chord, making the transition a little smoother.

It sounds like this:

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The key of A Major and how to use it.

The Diatonic Scale

If you’re thinking “the diet tonic what?”, don’t be alarmed. It’s pretty simple, and amazingly useful. Essentially, when you choose a key and scale, there is a diatonic scale that comes along for the ride. That means, there are other chords that exist in a happy relationship with your root chord. These are chords that, 9 times out of 10, will sound great in combination with your root, because they’re from the same scale.

Pro Tip: Scale Degrees.

We call these chords ‘scale degrees’ because they occupy a set position in relation to the root chord. For example, the scale degree 4, AKA ‘the fourth’ in A is E. There are 7 scale degrees in every diatonic scale.

One of the coolest things about Captain Chords is how straightforward it is to access these diatonic chords. They’re literally laid out on a plate for you to choose from. Simply enter any chord from the chord palette at the top of the screen, in a combination of your choice, and marvel at the awesome-sounding chord progression that comes out!

Here’s how the chord palette looks in Captain Chords:

A Maj diatonic

And here’s a chart of the diatonic scale of A Major:

Scale Degree Root 2nd 3rd 4th 5th 6th 7th
Chord name A Bm C#m D E F#m G° (Diminished)
Roman Numeral I ii iii IV V vi vii°

A nice chord progression using the diatonic scale of A Major:

A Maj nice prog

Borrowed Chords.

Now you know the rules of the diatonic scale of A Major, you can break them!

While the diatonic chords are guaranteed to sound great together, there are chords outside that palette that can also sound awesome. It really depends on the combination of chords together, and the length of time you spend on a borrowed chord. If you’re just passing over a borrowed chord on your way to a diatonic chord, it can sound great as it adds a little suspense. In reality, you can add any chords you like, it’s just a bit riskier when they’re out of the diatonic scale.

In this jazz-funk song by Deodato, the chord progression is just 3 chords. Two are from the diatonic scale of D Minor, with a passing chord which is ‘borrowed’ from another scale. The chords are Dm, F, Fm. It doesn’t always sound good mixing a minor and major of the same chord directly, but here it works because we always revert to the satisfying root, D Minor.

Explore the chord and scale of A with Captain Plugins.

It’s super easy to create your own ideas from scratch. Visit the official Captain Plugins homepage and see how it will help you explore music and write your own original productions.