A4 pages are to be punched with two holes 80 ± 0.5 millimeters apart, 12 ± 1 mm from the nearest edge of the sheet, symmetrically located between top and bottom, and 6 ± 0.5 mm in diameter. (ISO 838)
Ring binders are 290 by 320 mm. (ISO 623)
The length of the side along which the holes are punched is given first.
| Page Size | Hole dia. | No. of holes | Distance between centers |
|---|---|---|---|
| 11 by 8½ inches | ¼ inch or 5⁄16 inch | 3 | 3½ inches |
| 8½ by 5 inches | ¼ inch | 3 | 2¾ inches |
| 8½ by 6 inches | ¼ inch | 3 | 3½ inches |
A series of small ring binders called “memo books” have six rings. The paper is punched with 3⁄16 inch holes.
5 inches by 3 inches
6 by 3½ inches
6¾ by 3¾ inches
7¼ by 4¼ inches
Those with locks at top and bottom (double-lock rings) are generally of higher quality than those with only one or no lock.
Three styles of ring are used: round, elliptical, and D-ring. Elliptical rings are used in binders for a large number of pages: their advantage is that tabs are easier to read than they are with round rings. A D-ring metal is mounted on the back cover of the binder; it will hold about 25% more pages than round rings of the same size.
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Last revised: 11 August 2004.