The order of flats is:
B♭ E♭ A♭ D♭ G♭ C♭ F♭
But you can remain only:
B E A D G C F
How to memorize the order of flats
The trick is to memorize the word BEAD plus three letters GCF.
Another trick to memorize the orders of flats: Battle Ends And Down Goes Charles Father
Why to learn by rote the order of flats?
With the order of flats always in mind you will be able to do:
- Knowing all Altered notes in your music score (music notes with accidentals, flats in this case)
- Finding the name of the key signature.
Knowing all Altered notes
Imagine you have 4 flats in the key:
With the order of flats in mind, you immediately know the altered notes you will find in the score: B♭ E♭ A♭ D♭
G♭ C♭ F♭ and you will know that the previous score below is just like this:
Finding the name of the key signature
With the flats order, you can find the name of the key signature:
Imagine you have this (4 flats in the key)
With the order of flats, you have this: B♭ E♭ A♭ D♭
You find the second to last flat in this sequence: B♭ E♭ A♭ D♭, here it is A♭, so you know that the name of the key signature is A♭ Major.