DL envelope size in mm, cm and inches

DL envelope dimensions

Shape: length is 2 times the width.

DL stands for “DIN Lang” (German for “DIN long”); the size dates from the 1920s. Unlike C4, C5 and C6, DL is not part of the C series: it is a standalone size whose proportion is exactly 1 : 2.

What fits in a DL envelope envelope

The first fold that leaves at least 3 mm to spare each way is shown. “Does not fit” means no fold up to quarters fits.

Spare is the envelope dimension minus the folded sheet, in mm. Real envelopes vary a little between makers, and a thick insert needs extra room.

The DL envelope and the letter fold

The DL envelope exists to take an A4 sheet folded in three: 297 mm divided by three is 99 mm, so the folded letter is 210 × 99 mm and sits inside the 110 × 220 mm envelope with 10 mm spare across and 11 mm spare along. Fold the top third down, then the bottom third up over it. A US Letter sheet folded in three is 93.1 × 215.9 mm: it also fits, with 16.9 mm spare across but only 4.1 mm along, so it is a tight fit.

DL against C6/C5

The C6/C5 envelope (114 × 229 mm) is sold as “DL+” or “DL Plus” by some stationers. It is 4 mm wider and 9 mm longer than DL, which makes a folded A4 easier to slide in, and gives room for a thin leaflet. Both take the same A4 letter fold, but the window positions can differ, so check before buying window envelopes for a particular mail merge.

Flat items

A DL envelope will take an A6 card (105 × 148 mm) flat but not an A5 sheet; A5 folded in half to A6 fits, and A5 folded in three (70 × 210 mm) fits with 40 mm spare across and 10 mm along.

Frequently asked questions