How to know what scale you're playing in?

[Dennis1990]

When I hear a song I can tell which keys can be played for the song.

But I wouldn't know the scale its in without looking it up

Is there a quick way to find out which scale you're in once you find the keys???

 

[Rekordhead]

The root chord will tell you major or minor

 

[Wapiti]

Root chord will not always tell you major or minor, as you do not need to start your root chord on your root note. Best way to do it if you already know the notes is learn what pattern makes what kind of scale. Once you know how the scales are formed you can work backwards, examine the intervals of the notes you hear in the song and from there decide mode & Scale

 

[bandcoach]

you need to learn the pattern for each scale/mode - it is the only way to get there without making a mess of it along the way

the root chord can only tell you half the story as the following are possibilities for the two main chords we use to define a key

major ~ Ionian (major), Mixolydian, Lydian
minor ~ Dorian, Phrygian, Aeolian (natural minor), harmonic minor, melodic minor

patterns for each

Scale/Mode	Pattern	example on C	Major key of the given key signature
Ionian	T-T-S-T-T-T-S	C-D-E-F-G-A-B-C	C major
Mixolydian	T-T-S-T-T-S-T	C-D-E-F-G-A-Bb-C	F major ~ 1b
Lydian	T-T-T-S-T-T-S	C-D-E-F#-G-A-B-C	G major ~ 1#
Dorian	T-S-T-T-T-S-T	C-D-Eb-F-G-A-Bb-C	Bb major ~ 2b
Phrygian	S-T-T-T-S-T-T	C-Db-Eb-F-G-Ab-Bb-C	Ab major ~ 4b
Aeolian	T-S-T-T-S-T-T	C-D-Eb-F-G-Ab-Bb-C	Eb major ~ 3b
harmonic minor	T-S-T-T-S-T1/2-S	C-D-Eb-F-G-Ab-B-C	Eb major ~ 3b
melodic minor	T-S-T-T-T-T-S	C-D-Eb-F-G-A-B-C	Eb major ~ 3b

note that the harmonic and melodic minors alter the scale form from the natural minor but are considered to be still tied to the relative major key for the natural minor