Every time I see a lesson or a discussion about how to find the key of a song, I’m reminded that a lot of musicians have a remarkable gift…
... for making things way harder than they need to be!
All joking aside, the ability to work out the key of a piece of music quickly and accurately is an essential skill for every musician to have. However, as with many things, there are several ways this can be done and some approaches are harder (and slower) than others.
Most methods of working out the key require a relatively advanced understanding of music theory, an ability to read classical music notation, and/or access to the “official” sheet music. These requirements render many approaches impractical for most guitar players, and musicians who play in an improvised/jamming context like Blues.
With the method I want to show you today, you do not need to know lots of music theory to work out the key of a piece of music. You do not need to be able to read music notation, and you do not need to have access to any special abilities, tools or resources. All you need to work out the key of a song is:
1) Your ears,
2) Your guitar, and
3) A couple of simple scales
Before I show you how easy it is to work out the key of songs, let’s define what it is we’re talking about:
What does a song's Key actually mean?
It’s a term that is used all the time, but let’s start by making this word more concrete. The key of a piece of music is not some abstract concept or technicality of traditional music notation. The Key is literally this:
The SCALE the notes in the song come from
Every piece of music ever written uses the notes from one or more scales. A song’s Key means the main scale that piece uses. This is what a Key actually is.
For example, if a song is said to be “in A Major”, what we really mean is that it uses the A Major scale. If a song is “in C Minor”, then the melody and the chords come from the notes of the C Minor Scale.
Key names are scale names.
And just like scales, a key’s name consists of two parts:
ROOT NOTE + MUSICAL QUALITY
The Root Note is the starting note or home note of the key, which can be any note. The Musical Quality is the musical atmosphere or ‘mood’ of the key, and this can be either Major or Minor.
This is why key names are things like E Major, A Minor, Db Major, or G Minor. A key’s name is a specific letter note followed by either ‘major’ or ‘minor’.
Major keys are brighter and more joyful sounding than Minor keys, which are more dark and brooding. It’s a slight oversimplification, but you can think of Major keys as sounding essentially “happy”, and Minor Keys as sounding “sad”. Major and Minor are like musical-emotional opposites, and they contrast each other like day and night.
Now that we understand the basic idea of what a key is, let’s continue:
How to find the key of a song
To find the key of a song or piece of music you just need to work out two things:
1) Which note is the starting note of the scale (- the Root Note)
2) Whether the scale is Major-type or Minor-type
Let’s begin with how to recognise the starting note and most important note in any scale, the Root Note:
Step 1 - The Root Note
The Root Note is a fundamental principle of how music works, and it is the most important concept that you need to understand in order to correctly work out the keys of pieces of music.
I described the Root Note earlier as the starting note of the scale/key. It is, but it’s also a lot more than this. The Root Note is the one central note which all the other notes gravitate around and fall back to. The Root Note is the one note that sounds like “home”, in every piece of music. Picture the way the planets orbit around the Sun, and how everything depends on the Sun in the centre to create gravity. The Root Note is a bit like this:
At any given time, every piece of music ever written has — must have — a Root Note. Without the Root Note to establish a home base, musical notes and sequences would just sound like meaningless pitches; noises, not music.
How to identify the Root Note
The Root Note is something we hear, but also something we feel and sense. If we were to put on any piece of music and listen to it, we would find that at any given time there was one note that all the melodies and chords were gravitating around and falling back to. This sense of falling back to or returning home is called “resolving” in music, and this is the feeling we’re listening for to identify the Root Note.
Listen to a song you know well, and try to listen for that one note that stands out as being the one everything falls back to. This is the Root Note. It will often be repeating a lot more than others, or appearing frequently at the start or end of song sections. Hum, whistle or sing the note you think the music falls back to.
The Root Note has a unique property which marks it out when you find it — you can play it over entire sections of the song and it sounds like it fits well. If it ever sounds odd or out of place for a few seconds over a particular chord, you will hear it – if it is indeed the Root Note – “resolve” itself a moment later.
If you’re not sure then you can literally just start moving your finger up and down the low E string, picking different notes and humming them over the tune until you hit on one that sounds like it might be it. Once you find the note you think could be the root, it’s time for step two:
Step 2: Get out the Pentatonic Scales
Pentatonic Scales are simple five note scales that are extremely common in all styles of music. There are many ‘possible’ pentatonic scales, but the ones that we’re going to use to work out the key are the Minor Pentatonic and Major Pentatonic scales.
You may already know the Minor Pentatonic Scale, but you might not know the Major version as it’s slightly less common. Here are the patterns we’re going to use for these two scales:
The Minor Pentatonic Scale
The Major Pentatonic Scale
Take some time now to get familiar with these scale patterns if you aren’t already, because we’re going to be using them in the third and final step.
Notice how the Major Pentatonic has a bright, warm and cheery sound compared to the Minor Pentatonic’s edgier and more ‘badass’ sound. What you are hearing is the two contrasting sound qualities of Major and Minor in their most basic scale form.
With our pentatonic scales now at the ready, let’s move on to the final step:
Step 3: Test out the Root Note
Starting from the note you think is the root, play the Minor Pentatonic scale. If you’ve got it right then the scale will immediately sound cool, like it fits. Playing through its notes will sound like you could start improvising a bluesy rock solo to the song.
If the Minor Pentatonic scale fits with the song then congratulations; you’ve found the key.
Most blues-based rock songs are in a Minor key, so if you’re in this kind of style it makes sense to test your Root Notes with the Minor Pentatonic first.
There is another reason I always start testing Root Notes with the Minor Pentatonic Scale first. It’s a little involved to explain right now, but the upshot is that the Minor Pentatonic scale almost always sounds pretty good – even if the key’s quality is Major. The Minor Pentatonic is ‘cross compatible’ and often sounds good even in Major keys, but the reverse is not the case. This makes it ideal for identifying the correct Root Note.
If the Minor Pentatonic scale sounds off and doesn’t fit with the first Root Note you try, then pick another note you think it could be and try it with the Minor Pentatonic scale again.
If it still doesn’t work then you either have the wrong Root Note again, or you have the wrong scale. If you think you have the right Root Note but the scale sounds wrong, then that’s when to try out the Major Pentatonic scale.
Keys can only be essentially Major or Minor, so if you have the right Root Note then one of the Pentatonic scales is going to work. If neither scale works then you cannot have the right Root Note, so just find another note to try and repeat the process.
Finding the key by ear is always an imperfect art, but with some practice you will eventually be able to accurately identify the key of any song within a few seconds on your guitar.
With experience you’ll become very fast at hearing whether a song is in a Major or Minor key straight away from its overall mood, and then you can just focus on quickly narrowing down the right Root Note.
A lot of people think this is some kind of special ability when you can do it so effortlessly, but it’s a skill that you can learn and perfect.
And that's how it's done
Let’s quickly recap the process:
Step 1: Fish around for the Root Note
Step 2: Test it out with the Pentatonic Scales (Minor first)
Step 3: Repeat steps 1 and 2 until you find the key
The reason this works is that there are only 12 notes in music, and the key can only be Major-type or Minor-type, so you just test and re-test notes with the two scales until you find what fits.
And that’s it. That’s how you do it, and it works for all styles of music from the Beatles to Beethoven. No advanced Music Theory knowledge is required. In fact, it’s more like the other way around – this skill helps you make sense of Music Theory.
What if the key changes during a song?
No problem. If and when you sense the key of the song has changed (and you’ll know because the scale will stop fitting), then just repeat the process to find the new root note and key the song has moved to. Easy.
The world is now your jam track!
With this skill you won’t need to be told the key of things anymore, as you will be able to work it yourself. With some practice you’ll be able to put on any piece of music in any style and just pick up your guitar and start playing with it within a few seconds. Try it out and see how you get on!
PS If you want to check the key of a song you’re not sure of, ask me in the comments below or even send me an email. I love doing this and it only takes me a second or two to work it out, so I’m happy to help out if you’re unsure!