Find the Key of Any Song

Dear Students,
I hope you’re enjoying Guitar Lessons for the Curious Guitarist and continuing to learn a lot about playing the guitar. Today, I want to teach you a trick for finding the key of any random song in real time so you can solo along with it. This is a trick I learned very early on before I knew any music theory. This will help you develop your ear (ear training) and make you less dependent on written or verbal clues. It’s somewhat of a blunt force approach, but it totally works and you’ll get very fast at this after some practicing.

We are assuming that this is the first time we’ve ever heard this song and we don’t know anything about it – not the key, notes, chords, or even name of the song. In the beginning as you practice this, it’s ok to use a song (songs) that you already have so you can play it several times. Here’s what to do:

Start listening to the song. While listening, on your guitar, play the low E string open, picking that open note repeatedly several times for about 10 seconds. While doing this, you are listening to how that open E note matches up with the song you’re listening to. Next, repeat this process on the 1st fret of the low E string (the F note.) Next, repeat this process on the 2nd fret of the low E string (the F# note.) For each new note, you’re listening to how that note matches up with the song. (There is only one perfect note, the key note – that’s what we’re searching for.) We should continue this process, 10 seconds on each fret, until we reach the 12th fret. At the 12th fret, we either found the perfect note, or we missed it and have to start over again. (The 12th fret is the octave from open.)

At first this can be very frustrating. Choose any easy song with few changes to practice on. There will be three (3) notes between open E and 12th fret that will all sound good. This is because of the arpeggio. The intervals of the root note, 3rd (either major or minor), and the 5th will all sound like possible keys, but the root note will sound the strongest. That’s what we want! We want the best & strongest note. If we were playing the bass guitar and we could only play one note for the entire song, this is the note we want. If we’re correct, then we’ve found the key – hooray!

It’s very important to practice this on easy songs – songs that don’t have much going on. When I learned this, people listened to music on cassette tapes. I would listen to my song on cassette while looking for the key on the low E string, and the song would end and I still hadn’t found the key. Rewind and try it again – nope, didn’t find it, and the songs ended. Try again, and again. Eventually I would find it. It’s about listening carefully to the music and finding the most basic, simple, perfect note.

Now that we’ve found our key, we’ll try the pentatonic scales in that key. Let’s suppose our song is in the key of A. It’s probably in the major or minor scale – we still have to figure that out. So we’ll play the pentatonic major scale in A while listening to the song. Then we’ll try pentatonic minor scale in A while listening. (When the song ends, re-start it. You’ll probably re-start the song many, many times in the beginning.) One of the pentatonic scale will sound better than the other, as in, it matches with the song better. This will be the scale. Let’s suppose it was major pentatonic. So A major is the final answer and you should now re-start the song and solo from the beginning for fun!

You can go deeper into it by searching for the specific mode. Pentatonics will work perfectly 99% of the time. If it’s major pentatonic, the mode will probably be ionian (major scale) or the mixolydian. If it’s minor pentatonic, the mode will probably be aeolian (minor scale) or dorian. Remember to always start the scale or mode on the root note you found – don’t let scale finger positions fool you or mess you up.

As I said, this didn’t come naturally to me. I became a little faster after a few hours, and even faster after a few weeks. Now I can listen to the radio (or streaming whatever) with songs I’ve never heard before and find the key & mode in under 5 seconds. Then I solo and have fun with the new mystery music. You can do this too – it’s a learned skill.

This will eliminate your need for backing tracks, since any song can now be an instant backing track for you. Plus, this will start your journey into ear training for further details, like identifying the chords in the song…

I hope this makes sense to you. Start trying this out – it’ll change the way you listen to music from now on.

Talk with you more later,

-Dan (your guitar teacher)