US 3-Hole
Binders & Hole Punching · 6 specs
Direct Answer
The North American 3-Hole Standard is the ubiquitous paper punching system in the United States, Canada, and Mexico for 8.5 × 11-inch US Letter paper. Specifying three circular holes spaced exactly 4.25 inches (107.95 mm) apart (an 8.5-inch total span) with 5/16-inch (7.94 mm) hole diameters, it is the standard for 3-ring school and business binders.
Source: ANSI / Commercial Stationery Standards · Last reviewed Aug 28, 2026
Specs
| Center-to-Center Hole Spacing | 4.25 in (107.95 mm) |
| Total Outer Hole Span | 8.50 in (215.90 mm — from top hole center to bottom hole center) |
| Hole Diameter | 5/16 in (7.94 mm) standard or 9/32 in (7.14 mm) |
| Edge Distance to Hole Center | 0.375 to 0.50 in (9.5 to 12.7 mm) |
| Top & Bottom Margins on US Letter | Exactly 1.25 in (31.75 mm) from sheet edge to outer hole centers |
| Primary Applications | School 3-ring binders (Avery, Wilson Jones), corporate training manuals, loose-leaf filler paper |
Calculated Symmetry on US Letter
On an 8.5 × 11.0-inch US Letter sheet, the three holes divide the 11-inch vertical edge into two equal 4.25-inch spans, leaving exactly 1.25 inches (31.75 mm) of blank paper border above the top hole and below the bottom hole (1.25 + 4.25 + 4.25 + 1.25 = 11.00 inches).