I need some printed envelopes – what sizes do they come in?

  mm mm inches inches
C3 324 458 12 3/4 18
C4 229 324 9 12 3/4
C5 162 229 6 3/8 9
DL 110 220 4 1/3 8 2/3

This table lists the most popular sizes. Many other sizes are available – just ask.