Hole punch
Standards
In regions that use the US Letter paper format (8 1⁄2 by 11 inches, 220 by 280 mm); United States, Canada, and in part Mexico and the Philippines), a three-hole standard is widely used. The holes are positioned symmetrically, with the centers 4 1⁄4 inches (108 mm) apart. The diameter of the holes varies between manufacturers, with typical values being 1⁄4 to 5⁄16 inch (6 to 8 mm). The ​5⁄16 value is most commonly used, as it allows for looser tolerances in both ring binder and paper punching. The distance of the hole center to the paper edge also varies, with 1⁄2 inch (13 mm) being a typical value. Unlike ISO 838, this 3-hole system appears to have no well-established official specification, and is a de facto standard established by custom and tradition. It can only be applied to paper formats that are at least 9 1⁄2 inches (241 mm) high.
Hole punch-10