Determining the Key of a Song

Okay, since we’re talking about playing songs with other people, I couldn’t have asked for a better question to use first! Here we go:

Hello David;

I have a question for you – how can you tell what key a song is in? I thought that it was in the key of the first note or chord of the song, but that does not seem to hold true. I have a Fender GDEC Amp that has drum and bass background and there is a key switch to set what key the song is in. At times if I set it to the first chord the bass sounds fine, but at other times the bass notes seem not to match the chord I would be playing, so I am wondering if I am wrong for how to tell what key the song is in. I also have a song book that all the songs are suppose to be in the key of C, but some songs start with a Am chord or a F chord, etc.

Hope you can help me with this question, I really enjoy the Newsletter and the Pods that you and the people at Guitar Noise put out. Keep up the good work; it has helped me and, I am sure, many others.

Thank you.

Right off the bat, we need to establish a few things. What do we mean when we talk about the key of a song? This alone is something that many people quibble about. Let’s go with the obvious answer first – if you have a piece of sheet music (music notation, not just guitar tablature), then the key of a piece of music is given to you right at the start. It’s called the key signature, and you’ll find it just after the clef at the beginning of a line of music, like this:

Here you can see three flat symbols (they look like slightly squashed “b”s), which indicates that this particular piece is in Eb. You can find all twelve possible key signatures listed out for you in Your Very Own Rosetta Stone, as well as other articles on the Guitar Noise Beginners’ Lessons page.

Recognizing the key signature, though, is just one part of the puzzle, one we’ll return to in a moment after we deal with how to determine the key of a song when we don’t have the music handy.

And, naturally, this too requires a small diversion. Remember that music theory is never meant to be an answer as much as it is an explanation of why things are the way they are, music-wise – why we like certain combinations of sounds, why some chord progressions just seem meant for each other, things like that. There will always be exceptions to any “general rule,” sometimes thousands of them. That’s just the way it is.

Back on track – if you go on the assumption that the starting chord of any given song will be the key of your song, you will often be correct. Often enough to beat the house, in fact. But there are, as you’ve pointed out, more than enough exceptions that make using this method as a way to determine the key of a song questionable.

One of our old Guitar Columns at Guitar Noise, titled Five to One, explains keys as “feeling at home,” or having the sensation that it’s okay for a song to end at a particular place. Even more than the starting chord, the final chord should give one the satisfaction that the song has played out to a final conclusion. So if you look for the final chord of the song as being your indicator for the key to the song, you’ll do even better than you would by going by the first chord. Better still if the beginning and ending chords are the same.

But none of this is foolproof. Even having the key signature can occasionally put you on the wrong path. And we’ll pick up from this point next time…

Peace