Trick For Reading Key Signatures

Learning all of your key signatures is important if you want to master all of your major and minor scales, or if you're someone who enjoys improvising and wants to know about chord scales. Understanding which key you are in is a crucial first-step when learning to play any new piece of music, largely because you want to know in advance which notes will be sharps or flats, as opposed to having to constantly refer back to the key signature for reminders.

Many music students learn this fairly early on in their musical studies, but just in case any of you missed this nugget, I'm going to show you a little trick for reading key signatures.

When you look at a key signature, understand that the sharps or flats read in order from left to right, even though it looks like they are being written in an up-and-down pattern. Take this key signature, for example:

Trick for reading key signatures 1

The sharps written here are (in order from left to right): F#, C#, G#, D#, A#.

Here is the trick for finding out which major key you are in when reading a sharp key signature: Find the last sharp. Go up one half-step. This is your major key.

On the example above, the last sharp is A#. Going up one half-step from A# brings us to B. Therefore the key signature written is for the key of B major.

Let's try another one. What is the major key signature written below?

Trick for reading key signatures 2

There are three sharps - F#, C#, and G#. The last sharp is G#. Going up one half-step from G# brings us to A. Therefore, this key signature is the key of A major.


The trick for flats is a bit different. For flat keys: Find the second-to-last flat. This is your major key.

Try the flat-key example below.

trick for reading key signatures 3

Reading from left to right, the flats are Bb, Eb, Ab, Db, and Gb. The second-to-last flat is Db. Therefore, this is the key signature for Db major.

This trick will work for all but two of the twelve major key signatures. The exceptions are the key of C major (which has no sharps or flats), and the key of F major. F major has only one flat in its key signature - Bb. And since having one flat means there is no second-to-last flat, this key must simply be memorized.

trick for reading key signatures 4

So get started learning all 12 of your major-key key signatures, and try using this trick as often as possible!


9 comments on “Trick For Reading Key Signatures”

  1. Yes, this is great. In all my time with playing with improvisation and learning theory, I never came across this very simple tip. I appreciate it and echoed the sentiments of the previous poster: is there a similar tip for minor keys?

  2. A couple of interesting observations. The 7th to 8th step in a major scale is a half step so it makes sense that the key could be the next step up from the last sharp. But it could have also been the case that the next half step up would be the 4th of a scale. Why doesn't this happen? If you do go back from the last sharp three whole steps, you get the key of the next sharp which will be added. Why? The pattern ends when you get to the key of F# which has a E#!

  3. Wording is a little confusing on the five flats section. "Second to last" means Ab not Db (two removed from last place vs. one removed from last place). You should have written "next to last" to point to Db.

    Music notation is so hard to read for those of us not well versed in this material. You figure by now modern science would have come up with a better methodology on understanding musical tones or notes.

  4. There is another trick for flat keys that I use, that I believe works for every flat key. Take the last flat and count down 3 lines/spaces (not including the line/space with the last flat) and that will tell you what key you are in. Since you are talking about flat keys then you just add the flat. So, in the examples above, the last flat is Gb -> 3 lines/spaces down = D, so you are in Db. The other last flat, the only flat, is Bb -> 3 lines/spaces down = F, so you are in the key of F (not Fb - just F) <- an exception to every rule.

    That is how I do it. 🙂

  5. Thanks... I've not heard of this methods finding the key from the key signature, so much appreciated, and F is easy enough to remember.

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