ANSI C
North American (ANSI & Arch) · 6 specs
Direct Answer
ANSI C is an engineering paper standard defined by ANSI/ASME Y14.1, measuring 17.0 × 22.0 inches (431.8 × 558.8 mm). Formed by joining two ANSI B (Tabloid) sheets or four ANSI A (Letter) sheets, it is the entry format for mechanical CAD assembly drawings and electrical wiring schematics.
Source: ANSI/ASME Y14.1 (Drawing Sheet Size and Format) · Last reviewed Aug 28, 2026
Specs
| Width × Height (Imperial) | 17.00 × 22.00 in |
| Width × Height (Metric) | 431.8 × 558.8 mm |
| ANSI Hierarchy | ANSI C = 2 × ANSI B (Tabloid) = 4 × ANSI A (Letter) |
| Aspect Ratio | 1 : 1.2941 (17 : 22 — identical aspect ratio to ANSI A) |
| International ISO Equivalent | A2 (420 × 594 mm) |
| Primary Applications | Mechanical component CAD drawings, electrical control panel schematics, industrial plumbing diagrams |
ANSI Aspect Ratio Alternation
Unlike ISO 216 which preserves the constant √2 ratio across all sizes, the ANSI Y14.1 standard alternates between two distinct aspect ratios:
- ANSI A, C, E: 1 : 1.2941 (17 : 22 ratio).
- ANSI B, D: 1 : 1.5455 (11 : 17 ratio).
Because of this alternation, scaling an ANSI A engineering drawing up to ANSI B introduces margin letterboxing, whereas scaling from ANSI A directly to ANSI C is perfectly proportional.