ISO 838 (2-Hole)
Binders & Hole Punching · 6 specs
Direct Answer
ISO 838 (DIN 821) is the international standard for 2-hole paper punching, specifying two circular holes spaced exactly 80.0 mm ± 0.5 mm apart with a diameter of 6.0 mm ± 0.5 mm, positioned 12.0 mm ± 1.0 mm from the binding edge of the sheet. It is the universal standard for ring binders and lever arch files across Europe, Asia, Africa, and Latin America.
Source: ISO 838:1974 (Paper — Holes for general filing purposes — Specifications) / DIN 821 · Last reviewed Aug 28, 2026
Specs
| Center-to-Center Hole Spacing | 80.0 ± 0.5 mm (3.15 in) |
| Hole Diameter | 6.0 ± 0.5 mm (0.24 in) |
| Edge Distance to Hole Center | 12.0 ± 1.0 mm (0.47 in) |
| Centering Standard | Holes are centered symmetrically along the paper's long edge (A4) or short edge (A5) |
| Target Paper Pairing | ISO 216 A4 (210 × 297 mm) and A5 (148 × 210 mm) |
| Binder Compatibility | 2-ring binders, European lever arch files (Leitz Ordner, Esselte, Rexel) |
The 80 mm International Standard
Designed by Friedrich Soennecken (who patented the first hole punch Papierlocher für Sammelmappen in Bonn, Germany in 1886), the 80 mm spacing was formalized under DIN 821 and adopted globally as ISO 838. Because the holes are centered on the sheet's axis of symmetry, an A4 page (297 mm length) has its holes positioned 108.5 mm from top and bottom edges.
Why European Paper Fails in US Binders
An ISO 838 2-hole punched A4 document (80 mm spacing) cannot be filed in a US 3-ring binder (108 mm / 4.25 in spacing) without re-punching, which leaves unsightly overlapping ragged holes and weakens the paper margin.