How To Find The Key of A Song

In this tutorial, we're going to explore several techniques used to find the key of a song.

Knowing the key of a song is crucial because based on this element you can decide which chords and scales to play in the song's context.

There are methods that require music theory, such as checking sharps and flats on the staff, and more intuitive strategies, like looking for a dominant chord, that often resolves on the tonic. Let's dig in.

What Is The Key Of A Song

Let's first define some terminology: the terms key, tonic, root, chord I, are equivalent.

So, what is exactly the key of a song?

The key of a song is the chord that gives you a feeling of being at home, having resolved, coming to an end. It is the center, or tonic of the song.

For example, in the key of G major, the G major chord would be the tonic, or 1, chord.

Other examples: here below is the Key of C, notice chord I which is C and gives name to the key.

If you need a help in understanding lowercase and uppercase table headers, check Roman Numbers vs Nashville Number System tutorial.

Here's the key of G:

And here's the key of F:

Major And Minor Keys

There are two main kind of keys: major and minor keys. Major keys have a bright, joyful and happy feeling, while minor keys are used to create sad tunes and melancholic vibes.

As the names suggest, major keys are based on major scales, and minor keys on minor scales.

Please don't confuse the tonic with the first chord played in a song.

Many songs don't start on chord I. Some of them never use it at all.

The first chord of a song is not always the key (even if sometimes is)

Suppose you have a song that goes with Dm, F, Em and Am.

Well, all those chords belong to the key of C (see table above) so the song is in the key of C, even if C never appears!

Long story short, the key is named after the first note of the father scale, not after the first chord of the song!

Some Methods Helpful To Find The Key Of A Song

Analyze Sharps and Flats of the Key Signature

The most theoretical and rigorous approach is to check the sharp and flats on the score. Here below you find two tables that show you the several sharps and flats in each key:

Sharps

Flats

A useful device to observe how sharps and flats are placed along with keys is the Circle Of Fifths.

Look For A Dominant Chord That Stands Out

Dominant chords are a major chord plus a minor seventh, they are one of a kind. They contain a tritone and they desperately want to resolve into the tonic.

Wait..did I say tonic? Awesome, that means that every time you encounter a dominant chord, there is a strong probability that the next chord is the tonic, or key of the song.

Dominant chords are found at chord V of a major key, so to get to the tonic you count 5 back.

For example, the key of the classic three chord progression C, F and G7, is C.

Identify Chord Progressions

Chord progressions are often used as a pattern for a specific genre or style.

For example, the progression ii V5 Cmaj7 (Dm7, G7, Cmaj7 in the key of C) is the foundation of Jazz, so you can use this knowledge to guess the chord sequences, then chord I, thus the key. You find a complete guide on chord progressions here.

Other common chordal movements are ii-V (Dm to G in the key of C) and IV-vi (F to Am, in the key of C)

Compare The Chords Of The Song With a Keys Chart

You can check how many chords in the song are included in any of the keys shown on this page. There's a good probability that you'll find a key that contains all those chords.

If the majority of the chords falls in a key, apart from one or two, there's a possibility that the song uses some chords borrowed from another key.

It's Not Always so Easy: Things to Know

Of course, the devil's in the details, and often identify the key of a song is not so easy, for a number of reasons. It's a good idea to be aware of this issue. Let's examine what can happen in a song.

• A Song can change key: indeed, for example, a song can have the chorus in G major, and the rest in the key of C. A good idea is to refer to the Circle of Fifths and check the neighbor keys, which have only one sharp or flats different. You'll notice that the key of C is near to the key of G, and the only different note is F which becomes F sharp.
• Secondary dominants: Secondary dominants are non-diatonic chords (chords not present in the key) that are used to bring variations; the presence of a secondary dominant can complicate things as the following chord is not the key of the song.

How To Identify The Key of A Song: Conclusion

Ok, now you should have some strategies to put in action for finding the key of your favorite songs. Once you've identified the key, you'll know which chords and scales to play over those songs.

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