State whether A6 means paper or a US envelope
ISO A6 paper is 105 × 148 mm. C6 is 114 × 162 mm. A US A6 announcement envelope is 4 3/4 × 6 1/2 inches (120.65 × 165.1 mm).
Paper & card guide
Envelope for A6 paper
C6 is the familiar international envelope for ISO A6 paper flat. A US A6 announcement envelope is a different, larger format.
Nominal size reference
Compare the recorded formats
Every table uses nominal exterior width × height. International sizes lead with millimetres; US sizes lead with conventional fractional inches.
| Format | Native size (width × height) | Converted size (width × height) | Source checked | Context |
|---|---|---|---|---|
| C6International | 114 × 162 mm | 4.488 × 6.378 in | Envelope Manufacturers Association ↗27 August 2026 | A6 paper flat |
| A6 announcementUS announcement | 4 3/4 × 6 1/2 in4.75 × 6.5 in decimal | 120.65 × 165.1 mm | Neenah Paper ↗27 August 2026 | 4 1/2 × 6 1/4 inch card |
Original comparison
See the dimensional difference
The outlines use nominal face dimensions from the canonical records. They do not imply identical seams, flaps, usable capacity or manufacturing tolerance.
Choose from the real insert
C6 is the closer conventional match for a thin A6 sheet. The US announcement size adds more width and may suit a layered card, but the name alone is not a reason to choose it.
Nominal envelope dimensions describe the exterior format, not guaranteed usable internal space. Seams, lining, stock thickness, multiple pieces and manufacturing tolerances reduce practical room; sample before a bulk order or print run.
Naming is regional context, not equivalence
EnvelopeLogic keeps ISO paper names and US announcement envelope names separate throughout tables, links and matcher results.