Judging key from chord progression?

[MHarrisEP]

I'm working on a song, and it'd really be helpful to know what key I'm working in.

This seems like a really basic question, haha, so hopefully someone can tell me what key it is based on the progression, and explain how to find that.

I'm playing on a guitar with no capo, and the progressions are:

D - A - G - E and E - G - E - A - G

So, what key would that be? And how would the key change if I were to put a capo on the 2nd fret, for example?

Thanks ahead of time for any help. :]

[thebluemonk]

Make sure you describe the quality of the chord. There isn't always an absolute answer to the 'what key am I in' question, but in most cases you can get around 95% sure =). The complexity of your progression may depend on whether you have a E major or minor. I would probably lean toward D major with an Em.

A few terms to get you started on figuring out the key and chord choices for your future progressions:
http://en.wikipedia.org/wiki/Key_signature
http://en.wikipedia.org/wiki/Chord_quality (Scales and Chords section)
http://en.wikipedia.org/wiki/Chord_progression
http://en.wikipedia.org/wiki/Circle_of_fifths

Of course, there are many more factors that come into play (such as certain chords function in the progression), but you don't typically need to worry about it too much with simple triads.

As far as the capo (up 2 frets) goes, it shifts every note up 2 semitones. If you play the same chord shapes you did without a capo, you have effectively switched keys to the key 2 semitones above the original (lucky guitarists). For example, if you are in D major and you capo up 2 frets, and keep the same shapes, you are now in E.

[JonR]

Originally Posted by MHarrisEP

I'm working on a song, and it'd really be helpful to know what key I'm working in.

This seems like a really basic question, haha, so hopefully someone can tell me what key it is based on the progression, and explain how to find that.

I'm playing on a guitar with no capo, and the progressions are:

D - A - G - E and E - G - E - A - G

So, what key would that be?

Like bluesking said, it's helpful to know the quality of the chord - ie major or minor. (I'm guessing dim or aug are less likely ). Or are they just power chords?

As root notes alone, they could belong to various key scales: D, G, C or F major - or their relative minors.

But what really determines key is the sound. The keynote, or key chord, is the one that sounds like it is. That means the note or chord you would want to end the song on, and probably start it on. The chord that brings the sequence to a close, without leaving it hanging.

I can't tell that from what you've given. Not only is it not clear if the chords are major or minor, but there's no timings. The bar structure and the length of each chord can make a lot of difference as to which chord dominates, and that can matter in a song where the key scale is ambiguous (as it may be here).

Lastly: why do you actually want to know what key it's in? How would it help you? (That knowledge - IMO - won't help you either compose more or improvise on it.)

Originally Posted by MHarrisEP

And how would the key change if I were to put a capo on the 2nd fret, for example?

It would go up by a whole step. (Assuming you used the same chord shapes.)

[Malcolm]

OK how do you tell what key - the down and dirty - dirt simple way?

Look at the verse. What chord ends each verse. If it is the same chord for each verse that's your tonic chord thus the key. That chord will give the tonal center sound the guys are speaking of.

Beyond that I'm not sure we can tell you what key from the information you have given us. Too many choices remain as Jed mentioned.