A blues scale only has 6 notes; 5 notes from the minor pentatonic scale (here we go) plus one that sounds really whiny when overused.
If you’re looking for that bluesy feel, play the scale with the formula 3,2,1,1,3,2 frets up.
Every scale that has this ‘formula’ of frets between the notes is a blues scale.
Just find the tonic, play this formula of frets up (3,2,1,1,3,2) and you’ll be playing the blues scale.
A Blues Scale in the key of G would have these notes:
G, Bb, C, (Db), D, F, G.
‘Minor Pentatonic’ means exactly what it says.
It’s minor, meaning it contains a minor third in the scale.
This minor third can be found three frets up from the tonic
(a Bb in a G blues).
“Penta” is Greek for “five”, in this case, a scale containing five notes.
The added note which makes this scale a blues scale can be found 6 frets up from the tonic (or one string down, one fret up).
This flatted 5th in the scale should be used with taste.