SMG Guitar Lesson #10: What Key Are You In?

How often do the following situations happen to you?

  • You’re trying to figure out a song by ear. You have picked out a few chords, but there are a few chords that are still a mystery.
  • You want to learn a song and find some tabs/chords online, but they’re either dumbed down, in a  different key than the original, or simply inaccurate.
  • You’re learning a song and you want to write your own solo for it, and you want to be aware of all potential note choices so that you can have your own unique sound.
  • You’re writing a song, you have come up with a chord progression that sounds good and want to know what else you can add that will fit well with what you’ve done.

Now you’ve got to use your ear and your knowledge of music to take the next step and it starts with knowing what key you are in.

Knowing what key you are in has it’s advantages. If you play lead, you’ll be more aware of which scales you can use when improvising. And if you’re a songwriter, you’ll be better able to arrange and transpose a song to suit your needs. But knowing which key you’re in isn’t always an easy task… it’s even been known to elude a few professionals.

There are a few common misconceptions. The main thing to remember is that the chord that you start on isn’t necessarily the first chord of the key you’re in. There are seven basic chords in each key. That means that there is only a one-in-seven chance you’d be able to rely on that assumption. Quite frankly, your odds of success would be a little better playing a round of Russian roulette!

That’s why it is important to know what to look for when determining what key you are really in. And to do that, you will need to look a little more closely at how a major key is laid out, and make sure that you are aware of what it is about each key that makes it unique.


  • The I, IV, and V chords are all Major chords
  • The I and IV chords can become Maj7 chords
  • Only the V chord can become a V7 chord
  • The IV and V chords are only one step apart
  • The IV and V chords are on the opposite side of the circle from the I chord
  • The vi, ii, and iii chords are all minor chords and assume a similar “I-IV-V” relationship
  • all three minor chords become minor seventh chords in four-part harmony
  • the ii and iii chords are only one step apart
  • There is only one mb5 chord and only one m7b5 chord

These observations provide clues which you can look for in a chord progression that are a dead giveaway of what key you are in. Although we were only taking a look at the key of C major, the same is true for all major keys.

Of course there are exceptions to everything. There are all sorts of wild and crazy things that could happen in more advanced chord progressions that could throw you off. This includes: borrowed chords, secondary dominants, key changes, and blues/jazz chords, to name a few… actually, that’s a whole other lesson!

Make sure to take some time this week to familiarize yourself with the chords in a major key because we will get to all that other stuff before you know it!

Ready to start getting the most out of your playing? You can get you’re copy of my “Starters Kit” here:


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