It can be a little confusing as a beginner when you’re playing a song, but you don’t know what key it is.
It can be helpful to know if you’re trying to improvise a bit of lead onto the song, so we’ll look at finding the key today.
Here are some easy tricks we’ll look at in more detail:
- Does the song start and end on the same chord?
- Check the key signature
- Compare the chords in your song with chords in a key chart
- Finding the best fit
- Which chord resolves best?
As long as you can play a few chords and you have the internet or a chord chart, figuring out a key is very simple.
So let’s look into some of the ways to do this.
1. Does the song start and end on the same chord
While a lot of songs don’t start and end on the same chord, this is one way to find out.
If the first and last chord is the same, then they’re likely the root chord of the key.
There are some exceptions, but we’ll get into that after looking at the other tricks.
So if a song starts on G and has C, D, and G again, the key is likely G major.
2. Check the key signature
If you have the sheet music for a song and you can read sheet music.
The key of the song is always noted on the staff and you can use this to figure out which chords to play as well. Here’s a list of all the key signatures on sheet staves.
If you encounter sheet music and are unsure how to find the key, you can look at the notes played for the scale, or you can look at the sharps and flats.
Sharps are written that the sharp furthest to the right is before the key.
For example, G major has an F#, but D major has F# and C#, the C# is written furthest to the right and the next note after C# is D.
For keys where flats are drawn, it’s always the second flat from the right.
The only exception is in the key of F major, which has one flat in it (A flat). You’ll have to remember that one.
The same counts for playing in sharp keys.
You might play in the key of C# and find that the furthest note to the right is written on the stave as B#, but we know B# is C, and if you look to the note directly above the B line, you’ll find there is a # symbol sitting on it to the left.
3. Compare the chords with a key chart
If you have a key chart, you just need to look at the chords in your song and compare them in a chord chart.
Most of the time, you can find the four main chords that match up with the chord chart’s 1st, 4th, 5th, and minor 6th chords.
4. Find the best fit
Sometimes you might have a set of chords that appears to be in more than one key.
However, if you look at the chord that starts the progression- E minor, that tends to be the key.
Another example could be a progression that has chords outside of the key, for example, you could have C Eb, F, G.
No key contains all four of these chords, but C major contains C, F, and G, and then Bb contains Eb and F. So the best fit is C major.
5. Which chord resolves best
What does it mean for a chord to resolve?
When we play chords and play progressions, the progression of chords builds up tension, resolution in chords is simply the resolving of that tension.
Generally, the first chord of a key tends to resolve most of the tension.
The diminished 7th always reaches up to the first or tonic chord, but you won’t often see diminished chords in modern music.
However, the other chords in keys also tend to seek resolution through the tonic chord.
Can a song have multiple keys?
Yes, some songs have more than one key, and some of them have notable key changes. The Beatles often did this and you’ll often find it modern pop music.
How do you spot this though?
Well, oftentimes key changes do one of two things.
They either go a step up to the next key, for example, C major to D major, or they use a shared chord, for example, C and G both share A minor, and C major has the G chord in it too.
Is the first chord of a song always the one that names its key?
No, not always. Some songs might start on the fourth or fifth chord in the key, but you can tell by looking at that chord in the context of the rest of the progression.
For example, let’s say you have a progression that starts on D, but the other three chords played are G, E minor, and C.
Are you playing in D major or G major? C major isn’t in D major, so you’re playing in G, even though you started on D major.
How to know what are the notes of a key?
The fun thing about keys is that they’re linked to the scale.
For example, if you know the key of C has the chords CDEFGA and B, then you also have the notes. All the notes of C major are found in the chords of C major as well.
For example, if you were playing C, A minor, and G, you could find the majority of the notes for C major in these chords.
C has CEG, A minor has ACE and G major has GBD.
You’re only missing F which can be found in F major and D minor.
How to know if a certain key is major or minor?
Using the tricks we’ve learned, it can actually become quite simple to determine.
Let us take the progression E minor, C, G, and D for example.
You can compare it with the progression G, D, E minor, C.
Both have the same notes and chords, but the first chord gives a clue about which key is being used.
We could go a step further and consider the scale and how it’s being played and the mode being used.
Let’s say you’re playing the first progression that starts with E minor, but the scale and the riff being played tend to hang around on the notes G, D, and C more than anything.
Then you’re playing with a more major tone to the song.
However, Modality comes into play here, because if you’re playing in G major and you’re using E aeolian, then you’re going to have a very dark-sounding melody, even if it’s played over major chords.
When it comes down to it, G major and E minor are exactly the same as far as their chords, but they’re different in their mood.
E minor has a darker tone and G major is brighter. You could also consider that in the key of E minor, the 4th and 5th are A minor and B minor.
It’s not commonly played with those chords, but give it a try and notice how obvious the minor sound becomes.
Can the same chords appear on different keys?
Yeah, definitely. All keys share chords. C major shares F and G with their major keys.
This is partly how you can smoothly transition between keys, by playing the chords they have in common.
If you wanted to shift from C to G, you could either play a progression in C major that emphasizes the G chord or you could play a progression that uses the A minor and E minor chords along with G.
So let’s say you played C, A minor, F, G, you could then play C, A minor, E minor, G, and then C, G, D, E minor and you’d have successfully switched keys.
Are the key and the scale of a song the same thing?
Almost, but not quite.
The key of a song is a scale that starts at a specific note, while the scale of a song is the sequence of notes played at specific intervals.
For instance, you can play the major scale sequence that starts on the C note, and you’ll be playing in the key of C major.
If you stay at C and play a minor scale or a melodic minor or a harmonic major or a minor pentatonic, you’d be playing those scales, but you’d still be in the key of C.
It would just be the key of C minor or C melodic minor and so on.
I hope this cleared up some of your questions about finding the key of a given song and some caveats that you might consider.
Hello there, my name is Ramiro and I’ve been playing guitar for almost 20 years. I’m obsessed with everything gear-related and I thought it might be worth sharing it. From guitars, pedals, amps, and synths to studio gear and production tips, I hope you find what I post here useful, and I’ll try my best to keep it entertaining also.