How do i determine the key of a song?

[rnhodu]

Hey all. I have been checking out these boards for some time, truly thankful for what has been provided via them, just wondering if i might ask a simple music theory question:
How do i determine what key a song is in? Is it based on the first chord that i play in the song? Or is it something more advanced than this? More specifically, what key is "Best of what's around" in?
Thanks so much.
-Ryan.

[Mathers420]

I don't know much about theory, but I believe the easiest(but not always acurate way) is just the first chord that is played in each part of the song (the verse and chorus and bridge could all be in different keys)

This is not always the case, but unless you wanna learn music theory (which I haven't) it's about 90% accurate.

[winglet82]

One thing I look for is the 1-4-5 chords. Most songs in a major key are written around the 1-4-5 chords. For example, let's say a song is in the key of C. That would mean it is written in the C major scale: C-D-E-F-G-A-B-C. to find the 1-4-5 chords, start with the first letter and cound each number: 1 (C), 4 (F), 5 (G). So the three main chords you should see in a song in the key of C are C, F, and G. Here are some other common keys and their 1-4-5 chords:

A: A, D, E
C: C, F, G
D: D, G, A
E: E, A, B
F: F, Bb, C
G: G, C, D