A sizes

A6: 105 x 148mm
A5: 148 x 210mm
A4: 210 x 297mm
A3: 297 x 420mm
A2: 420 x 594mm
A1: 594 x 841mm
A0: 841 x 1189mm

SRA sizes

SRA4: 225 x 320mm
SRA3: 320 x 450mm
SRA2: 450 x 640mm
SRA1: 640 x 900mm
SRA0: 900 x 1280mm

SIGN sizes

Full sheet ACM or corflute: 2440 x 1220mm
Half sheet ACM or corflute: 1220 x 1220mm
“Real Estate” Corflute: 600 x 900mm

OTHER sizes

DL: 99 x 210mm  ~ Common Flyer or Rack Card = 1/3 of an A4
DLE: 114 x 225mm ~ Common envelope size suitable for 1/3 A4 (as above)
C4 Envelope: 229 x 324mm ~ Standard envelope size for A4 paper