Nashville Numbering System

Here you go. Figure out song chords, transpose stuff into other keys, or just enjoy the amazing math that is music! Speaking of which, check out the Circle-of-Fifths Calculator for a really fun way of digging into this. Enjoy!
—Yer pal,

Major Keys I II III IV V VI VII
A A Bm C#m D E F#m G#dim
B B C#m D#m E F# G#m A#dim
C C Dm Em F G Am Bdim
D D Em F#m G A Bm C#dim
E E F#m G#m A B C#m D#dim
F F Gm Am Bb C Dm Edim
G G Am Bm C D Em F#dim
Minor Keys I II III IV V VI VII
Am Am Bdim C Dm Em F G
Bm Bm C#dim D Em F#m G A
Cm Cm Ddim Eb Fm Gm Ab Bb
Dm Dm Edim F Gm Am Bb C
Em Em F#dim G Am Bm C D
Fm Fm Gdim Ab Bbm Dm Db Eb
Gm Gm Adim Bb Cm Dm Eb F

Helpful video from Austin Scelzo: