US Letter
North American (ANSI & Arch) · 7 specs
Direct Answer
US Letter (ANSI A) is the standard business and consumer paper size in the United States, Canada, and parts of Mexico, measuring exactly 8.5 × 11.0 inches (215.9 × 279.4 mm). Standardized under ANSI/ASME Y14.1, it is slightly wider and shorter than the international ISO 216 A4 format.
Source: ANSI/ASME Y14.1 / NIST / US Federal Standard 006 · Last reviewed Aug 28, 2026
Specs
| Width × Height (Imperial) | 8.50 × 11.00 in |
| Width × Height (Metric) | 215.9 × 279.4 mm |
| ANSI Series Designation | ANSI A (Base engineering format) |
| Aspect Ratio | 1 : 1.2941 (17 : 22 — not √2) |
| Comparison to ISO A4 | US Letter is 5.9 mm wider and 17.6 mm shorter than A4 (210 × 297 mm) |
| Standard Office Weight | 20 lb Bond (approx. 75 gsm) or 24 lb Bond (approx. 90 gsm) |
| Matching Envelope Standard | US #10 Envelope (4.125 × 9.50 in / 104.8 × 241.3 mm) |
Historical Origins: The Vatman's Reach
Unlike ISO A4's mathematical √2 derivation, the 8.5 × 11 inch US Letter size originated in early hand papermaking: a typical vatman's arms could comfortably dip a double mould of 17 × 22 inches (the 'Demy' size). Cutting this master sheet in quarters produced four 8.5 × 11 inch sheets. In the 1980s, President Ronald Reagan mandated 8.5 × 11 as the official standard for all US federal government agencies, discontinuing the historical 8.0 × 10.5 inch 'Government Letter' format.
Cross-Border Printing Challenges
Because US Letter (215.9 mm wide) is wider than A4 (210 mm), printing a US Letter document on an A4 printer without scaling cuts off side margins. Conversely, printing an A4 document (297 mm tall) on US Letter (279.4 mm) cuts off footers and page numbers.