What Is A DL Envelope? Marketing Team Updated March 16, 2022 12:24 Follow What Size Is A DL Envelope In mm? DL is a standard envelope size measuring 220 x 110 mm. They fit A4 sheets folded into three. Learn more about our envelopes range here. Related articles Paper & Envelope Sizes UK How To Design For Print How to use our Email Templates How to supply Folded Leaflet artwork Paper sizes A0 - A10 Comments 0 comments Article is closed for comments.