How to Transpose Down a Major 3rd: A Music Theory Guide

By Jade Bultitude
Last Update:

Transposition is essential skill for any aspiring musician. At their heart of it, transposition allows you to alter music so that it can be played on different instruments or in different ranges of pitch.

So let’s take a dive into how to transpose down a major 3rd. This is both for music theory students and for musicians seeking to understand the concept of transposition.

Need to transpose using another interval; check out all our transposition guides here.

What is a Major 3rd?

A major 3rd interval is created when we move from the 1st degree of the scale to the third degree to the scale. This interval is called a ‘major’ third because it is the 3rd note of the major scale.

Another way of thinking about a major 3rd is that it is 2 whole-steps above the lower note.

down a major 3rd C to A flat

It’s worth remembering that 2nd, 6th and 7th intervals can also be major or minor, whereas 4th and 5th intervals are described as ‘perfect’.

How to Transpose Down a Major 3rd

This method has three steps:

  1. Transpose the key signature down a major 3rd
  2. Move all the notes down a 3rd
  3. Deal with the accidentals

(If you thought we could transpose each note one at a time, click here to see why NOT to do this)

Let’s try an example. Have a look at the melody below and let’s transpose it down a major 3rd.

c major melody for transpose down a major 3rd

Step 1- Transpose the Key Signature

First, let’s transpose the key signature. Our melody is the key of C major, so what is a major 3rd below C natural?

a flat major scale with down a major 3rd highlighted

As you can see above, a major third below C is A flat. This means that we now need to put the key signature of Ab major at the start of our melody. 

The key signature of Ab major has four flats- Bb, Eb, Ab, Db.

F natural minor scale key signature treble clef

Here it is in our melody.

melody in A flat major
  • If you are still unclear on your key signatures, please make sure you are familiar with your Circle of Fifths

Step 2- Move the notes Down a 3rd

Once you have changed your key signature, we then need to follow this with moving all the notes in the melody down a 3rd. As with all intervals we include the starting note, so effectively this means moving the notes down twice.

melody in a flat notes moved down a 3rd

And we have our transposed melody! Below is the original melody with the tranposition underneath.

There are no accidentals in this melody so no need for step 3 this time.

Here is the complete transposition with the original and new melodies.

transpose down a major 3rd original and new melody

Example 2

What key is our melody in below?

melody in d major for transpose down a major 3rd

That’s correct, we are in D Major!

Step 1- Transpose the key signature

First let’s transpose the key signature. Can you transpose down a major 3rd from D?

b flat major scale with 3rd highlighted

The 3rd note of the B flat major scale is D natural. This means we now need the key signature of Bb major. Bb major has two flats – Bb and Eb.

G natural minor scale key signature, treble clef

Here is the new key signature at the start of our melody.

melody in b flat major with key signature highlighted

Step 2- Move the Notes Down a 3rd

Now we have changed the key signature, simply move all of your notes down a 3rd. 

melody in b flat with notes moved down a 3rd

As you can see, we have not moved the E sharp note yet. This is because it is not in the notes of the original key signature and so will need to be treated differently.

Step 3- Accidentals

In our original melody we have an E#. This note is not in the key of D major and so it will not be transposed correctly be the first 2 steps.

To transpose this note we treat it on its own. We can ask: what is a major 3rd below E#? E# is an awkward note to transpose as it does not appear in most keys. So, how do we move this note down a major 3rd?

The easiest method in this case would be to lower the E# a half-step to an E. Finding a Major 3rd below E is much easier: it is C natural. Then we raise the C back up a half-step to correct it to C#.

major 3rd, e to C and E sharp to C sharp

Can we transpose one note at a time?

This is the slowest method of transposing, but it works! Here we are going to move each note down a major 3rd interval to create our transposed melody.

melody transposed down a major 3rd note by note

Remember that for each different note we need to count down a 3rd in a different key. Because of this it can be way easier to make mistakes. You will also need to look at your notes to figure out the key signature for your new melody, otherwise you may have a lot of accidentals to read!

What’s next….?


How can I transpose sheet music up a perfect 5th automatically?

There are a variety of apps that can transpose sheet music such as Sibelius and Musescore.

What about transposing a piece in a minor key Down a major 3rd?

If you have a piece in a minor key then transposition works much the same. Remember that a minor piece will be transposed into another minor key even through we are moving it down a major 3rd. (Similarly a piece with a major key signature will be transposed to another major key).

For example, a piece in A natural minor would be transposed into the key of F minor (four flats – Bb, Eb, Ab, Db). This is because A natural is the 3rd note of the F major scale.

In a way it’s easier to think of the original key signature without the major/minor label. If the piece is in A minor, just start with the note A natural and transpose from there. Just remember pieces do NOT change whether they are major or minor by transposing them.

Important- beware of accidentals as these need to be treated independently. Scales such as the harmonic minor and melodic minor use additional accidental outside the key signature.

What is a major 3rd interval?

I major 3rd is the the interval created by the root note and the 3rd note of the major scale. It could also be thought of as being 4 half-steps above the root. When working out your intervals make sure to remember the key signature of your root note!

Below are several examples of major 3rd intervals.

examples of major 3rd intervals in Gb major and E major
Photo of author
Jade is a flute player and music educator with a passion for educating the next generation of musicians. She is a Masters Graduate from Trinity Laban Conservatoire of Music and Dance. Jade has been helping people learn music theory for more than 10 years from pre school children all the way to degree level studies.