Telling The Key

How to tell the key of a piece of music

There are several situations in music theory — and many situations in music generally — where you will need to be able to tell the key of the music. Normally, you would expect the key signature to reflect the key, but this is not always the case, especially if the new key is reached by modulation.

Here is a 5-step technique you can use to identify the key:

Step #1

What is the key signature?

The key at the beginning and end of a piece of music is likely to be indicated by the key signature, which will give two possibilities: a major key and a minor key.

Step #2

What is the note in the bass at the beginning and end?

Often, this will be the tonic note of the scale. If there is no bass — just a melody — what note does the melody end on?

Step #3

Are any triads outlined in the melody?

Often, especially at the beginning and end, these will be triads built on the tonic.

Step #4

Is the music in the major or minor?

You can spot a minor key because the harmony will feature a raised 7th degree, and the melody also a raised 6th degree.

Step #5

Test your ideas.

From steps 1-4, you should have a good idea of the key. Now test it: do the notes in the music fit the scale of the key you have selected?

Bear in mind that there are several possibilities in the minor key, but a phrase rising to the tonic will always have a raised 7th degree (and probably also a raised 6th degree).

If the notes do not fit the scale of the key you have chosen, then you might have the key wrong. Check back on steps 1-4 and see if another key fits better.

Practice!

Try and learn these five steps by heart and develop an instinct for them. The best way to do that is to practice: just try the technique on any piece of music you have handy, or try opening a hymn-book (or other book with lots of different pieces) at random pages!

A test

Here's a quick question for you to practice with straight away.

Q. In which key is the following music? (Greensleeves, trad.)

Greensleeves, trad.
Click to reveal the answer...

Answer: B minor

If you followed the 5-step technique, it should have gone something like this:

  1. 2 sharps: D major or B minor
  2. No bass, but the first note is B and the last note is also B.
  3. Yes: I can see A major (bars 3-4) and F sharp major (7-8). Not much help!
  4. The raised 7th degree of B minor would be A sharp. Aha! That F sharp major triad has an A sharp!
  5. Test it: As it's a melody, let's look for B melodic minor. Aha! The melody ends with a G sharp, A sharp, and B: that would fit the 6th and 7th degrees of B melodic minor, ascending, followed by the tonic! They would not fit D major at all however.

So our answer is B minor — which happens to be correct!

The next Clements Tip will be with you soon — keep an eye on your inbox!

Not a subscriber? Get your FREE 40-part email course here

Did you like this tip?

You'll find lots more on the Clements Theory website:

  • 80 step-by-step study guides from the basics to Grade 5 and beyond
  • Revision questions to test your comprehension of each guide
  • Over 7000 practice questions organised by difficulty and topic
  • The Clements Q&A — rapid assistance from a music theory expert!
  • Track your progress with the clever Clements Theory tools: see instantly where you are improving and where you need to practice more

Clements Theory is perfect for anyone studying for Associated Board or Trinity College Theory of Music Exams (Grades 1 to 5), and for GCSE or A Level Music.

“I've finished my theory exam and passed with Distinction,
thanks so much for your help!! ”

— Carmen Guthrie
Clements Theory user and successful Grade 5 Theory candidate

“Thank You, I have passed my theory exam,
I found Clements Theory very helpful!”

— Stephanie Hunter
Clements Theory user and successful Grade 5 Theory candidate