Paper Sizes
A6 105 x 148 mm is quarter the size of A4
A5 148 x 210 mm is half the size of A4
A4 (Standard copy paper) 210 x 297 mm
A3 297 x 420 mm is twice the size of A4.
A2 420 x 594 mm is twice the size of A3, and four times the size of A4.
A1 594 x 841 mm is twice the size of A2, and eight times the size of A4; and
A0 is twice the size of A1, and sixteen times the size of A4.
Envelope Sizes
C6 envelope fits an A6 sheet of paper, A5 sheet folded in half or an A4 sheet folder in quarters
DL envelope fits an A4 sheet folded in thirds
C5 envelope fits an A5 sheet, A4 sheet folded in half, or an A3 sheet folded in quarters
C4 envelope fits an A4 sheet, or A3 sheet folded in half
Paper Folds
