Opening-side guide
A booklet envelope normally opens on the long side; a catalog envelope normally opens on the short side. The same nominal rectangle can therefore be offered in either construction.
Nominal size reference
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 |
|---|---|---|---|---|
| 9 × 12 bookletUS booklet | 9 × 12 in9 × 12 in decimal | 228.6 × 304.8 mm | Neenah Paper ↗27 August 2026 | US Letter paper flat with generous nominal space |
| 10 × 13 bookletUS booklet | 10 × 13 in10 × 13 in decimal | 254 × 330.2 mm | Neenah Paper ↗27 August 2026 | open side |
| 9 × 12 catalogUS catalog | 9 × 12 in9 × 12 in decimal | 228.6 × 304.8 mm | Neenah Paper ↗27 August 2026 | US Letter paper flat with generous nominal space |
| 10 × 13 catalogUS catalog | 10 × 13 in10 × 13 in decimal | 254 × 330.2 mm | Neenah Paper ↗27 August 2026 | open end |
Open-side booklet construction can suit inserting sets along a long edge. Open-end catalog construction can suit feeding a stack through the short edge. The choice is operational rather than a change in the nominal rectangle.
A 9 × 12 inch format provides nominal space around US Letter paper placed flat. A 10 × 13 inch format adds room for thicker or larger sets, but the usable interior still depends on 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.
Gussets, expansion seams, closures, windows and reinforcement alter usable capacity. EnvelopeLogic does not infer capacity or postal eligibility from the nominal face size.