Envelope No. 9 paper size
98.425 × 225.425 mm
3.88 × 8.88 inches · 9.84 × 22.54 cm · aspect ratio 1:2.29
Envelope No. 9 size is 98.425 × 225.425 mm. Those are the Envelope No. 9 dimensions a printer works to; the same sheet in centimetres, inches, points and pixels is below.
What Envelope No. 9 is for
Envelope No. 9 is 3⅞ × 8⅞ inches, or 98.425 × 225.425 mm. The reply envelope, cut a quarter of an inch narrower and five eighths shorter than a No. 10, so that it slides inside one without being folded. That is the whole reason it exists, and why billing envelopes arrive in pairs.
Envelope No. 9 dimensions in every unit
| Unit | Width | Height |
|---|---|---|
| Millimetres | 98.425 mm | 225.425 mm |
| Centimetres | 9.84 cm | 22.54 cm |
| Inches | 3.88 in | 8.88 in |
| Points (PostScript) | 279 pt | 639 pt |
Envelope No. 9 in pixels
Pixel dimensions depend entirely on the resolution you are working at — there is no single "pixel size" for a sheet of paper. Every resolution, with file sizes and canvas setup →
| Resolution | Pixels | Use |
|---|---|---|
| 72 DPI | 279 × 639 | Screen preview only — far too coarse to print |
| 150 DPI | 581 × 1331 | Draft printing, internal documents |
| 300 DPI | 1163 × 2663 | The standard for commercial print |
| 600 DPI | 2325 × 5325 | Fine detail, line art, archival scanning |
Setting up a print document? Use 300 DPI and add 3 mm of bleed on every edge unless your printer specifies otherwise.
How Envelope No. 9 relates to the rest of the series
At 98.425 × 225.425 mm (3.88 × 8.88 inches) the aspect ratio is 1:2.290. US envelopes are not a halving series: each size is cut to hold a particular sheet or card, so the numbers step irregularly and nothing scales cleanly to anything else.
Of the standard sheets on this site, the largest that goes in flat is Index Card 3×5 at 76.2 × 127 mm, with a few millimetres to spare on each edge.
Folded, the largest standard sheet it takes is a Letter sheet folded in three.
About Envelope No. 9
3.875 × 8.875 inches. The US reply envelope, sized to slip inside a No. 10 unfolded.
Other US envelope sizes sizes
| Size | Millimetres | Inches |
|---|---|---|
| Envelope No. 10 | 104.775 × 241.3 mm | 4.13 × 9.5 in |
| A7 Envelope (US) | 133.35 × 184.15 mm | 5.25 × 7.25 in |
| A1 Envelope (US) | 92.075 × 130.175 mm | 3.63 × 5.13 in |
| A2 Envelope (US) | 111.125 × 146.05 mm | 4.38 × 5.75 in |
| A6 Envelope (US) | 120.65 × 165.1 mm | 4.75 × 6.5 in |
| A8 Envelope (US) | 139.7 × 206.375 mm | 5.5 × 8.13 in |
| A9 Envelope (US) | 146.05 × 222.25 mm | 5.75 × 8.75 in |
| A10 Envelope (US) | 152.4 × 241.3 mm | 6 × 9.5 in |
| Envelope No. 6 3/4 | 92.075 × 165.1 mm | 3.63 × 6.5 in |
| Envelope No. 11 | 114.3 × 263.525 mm | 4.5 × 10.38 in |
| Envelope No. 12 | 120.65 × 279.4 mm | 4.75 × 11 in |
| Envelope No. 14 | 127 × 292.1 mm | 5 × 11.5 in |
Frequently asked questions
What size is Envelope No. 9 in mm?
98.425 × 225.425 mm.
What size is Envelope No. 9 in inches?
3.88 × 8.88 inches.
What size is Envelope No. 9 in pixels?
There is no single answer — it depends on resolution. At the print standard of 300 DPI it is 1163 × 2663 pixels; at 72 DPI it is only 279 × 639.