Same characters, different systems
In US stationery, A7 is an announcement or invitation-envelope name. In the ISO paper series, A7 is a small trimmed paper size. The envelope is not named because it fits ISO A7 paper.
Naming disambiguation
US A7 envelope vs ISO A7 paper
US A7 envelope and ISO A7 paper are unrelated labels. The envelope is 5 1/4 × 7 1/4 inches (133.35 × 184.15 mm); ISO A7 paper is 74 × 105 mm.
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 |
|---|---|---|---|---|
| A7 invitationUS announcement | 5 1/4 × 7 1/4 in5.25 × 7.25 in decimal | 133.35 × 184.15 mm | Neenah Paper ↗27 August 2026 | 5 × 7 inch card or photo |
How to write the specification safely
Use “US A7 invitation envelope, 5 1/4 × 7 1/4 in” when you mean the envelope. Use “ISO A7 paper, 74 × 105 mm” when you mean the paper. Include both the regional/system label and dimensions.
What the US A7 commonly fits
The familiar insert relationship is a 5 × 7 inch card or photo. That still requires practical clearance and a check of stock, layers and envelope construction.
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.