Guitar Chords in the Key of G Major

The chords in the key of G Major

G Major Chord G
A minor Chord Am
B minor Chord Bm
C Major Chord C
D Major Chord D
E Minor Chord Em
F Sharp Diminished Chord F♯dim

G Major - A minor - B minor - C Major - D Major - E minor - F♯ diminished (F♯°).

      G     Am    Bm    C     D     Em    F#dim 
      I     ii    iii   IV    V     vi    vii   

The chord formula for any Major key is
Major - minor - minor - Major - Major - minor - diminished

A common way to number these chords is by Roman numerals
I - ii - iii - IV - V - vi - vii

(Major chords are usually capitalized, minor and diminished chords are lower case)