#2
you go by the dominant note being played
Quote by Jack Off Jill
Man, thank God the russians created UG. Otherwise, how would I have gotten this information?
#3
Figure out the chord progression and that will tell you. Or just play around in different keys until one of them doesn't hurt your ears.
#5
There is a "correct way" to determine the key of a song, but it involves a lot of theory (namely, chord construction, scale construction, and harmonizing a major scale) and a post containing all of that info would take a long time to write. I can write all that out if you want to see it, but it is a bit overkill if all you want to do is find the key of a simple song. In general, though, if the key isn't given just use your ear and, unless you primarily play jazz or any other style of music with complex progressions and an abundance of key modulations, you should be fine finding what key the song is in.
#7
knowing some theory would be helpful.
without that, listen for major cadence/resolution in the song, especially in chorus sections.
the chord resolved to is probably the key. (but not always the case)

try playing these basic progressions to see if you can hear what I'm tyring to say...
G - C - D - G.... or, G - Em - Am - D
in both cases you should hear the D "leading" your ear back to G.
(sorry this is hard to put into words)
#8
Quote by cringer
the chord resolved to is probably the key. (but not always the case)

Actually, it is always the case.

Find out the chord that the progression resolves to (i.e. the tension is relieved). That is the key of the progression. This is an easy and accurate method.
E:-6
B:-0
G:-5
D:-6
A:-0
E:-3
#9
Quote by Flibo
Actually, it is always the case.

Normally yes, but not 100% of the time. Not every song in the world.
therefore not always the case.
#10
Quote by A_man13
There is a "correct way" to determine the key of a song, but it involves a lot of theory (namely, chord construction, scale construction, and harmonizing a major scale) and a post containing all of that info would take a long time to write.

Fortunately, this has been done in a series of articles called 'The Crusade'.

http://www.ultimate-guitar.com/columns/general_music/the_crusade_part_7_analyzing_a_chord_progression.html

You'd probably need to go to his earlier articles in the series to know what he's talking about if you have absolutely no idea what he's explaining. In which case, go here: http://profile.ultimate-guitar.com/JoshUrban/contributions/.
#11
Quote by triface
Fortunately, this has been done in a series of articles called 'The Crusade'.

http://www.ultimate-guitar.com/columns/general_music/the_crusade_part_7_analyzing_a_chord_progression.html

You'd probably need to go to his earlier articles in the series to know what he's talking about if you have absolutely no idea what he's explaining. In which case, go here: http://profile.ultimate-guitar.com/JoshUrban/contributions/.


I was going to post that link too. If you have the time, it's a great set of articles to read if you ever want to learn theory.