Cutter Size

Cutter sizes are represented in various ways: U.S./metric; wire gauge ranging from 80 (0.0135”/0.343mm) to 1 (0.228”/5.791mm), and letters ranging from A (0.234”/5.944mm) to Z (0.413”/10.49mm). These conventions measure the size of the hole, and have been standardized across manufactures. For example, to drill a half-inch diameter hole, select a drill bit labeled one-half inch in diameter. Using the metric system, to drill a hole 10mm in size requires bit sized to 10mm.