The No. 9 envelope is a staple of American business correspondence, widely used as a return envelope for bill payments, invoices, and subscription renewals. Because its dimensions are slightly smaller than a standard No. 10 envelope, it is designed to fit perfectly inside one without being folded. This makes it an ideal choice for companies including a pre-addressed, stamped envelope to encourage quick and convenient replies from customers.
| Width (*) | 225.43 mm |
| Height (*) | 98.43 mm |
| Standard | US Office Envelope |
| Aspect Ratio | 1:2.2903 |
(*) Subject to orientation
No. 9 Envelope
| Unit | Width | Height |
|---|---|---|
| Millimeters (mm) | 225.43 | 98.43 |
| Centimeters (cm) | 22.54 | 9.84 |
| Meters (m) | 0.23 | 0.1 |
| Inches (in) | 8.875 | 3.875 |
| Points (pt) | 639.01 | 279.01 |
| Picas (pc) | 53.25 | 23.25 |
| Pixels @ 72 DPI | 639 | 279 |
| Pixels @ 96 DPI | 852 | 372 |
| Pixels @ 300 DPI | 2663 | 1163 |