Quarterinch

Quarterinch is a term used to denote a length of 0.25 inches (one quarter of an inch). In decimal form, it is 0.25 in and equals 6.35 millimeters. It is part of the United States customary units and is common in regions that use the imperial measurement system. The notation 1/4 in, ¼ in, or 0.25 in is commonly used.

In practical use, a quarter inch appears in numerous trades. In sewing, a quarter-inch seam allowance is a standard measurement for many patterns. In woodworking and metalworking, 1/4-inch dimensions are common for gaps, stock sizes, and drilling or routing operations, and 1/4-inch drill bits or router bits are widely available. Hardware and fasteners may be specified by nominal 1/4-inch sizes, and dowels or plugs may be cut to 1/4 inch diameter.

In tools and equipment, the term also appears in the quarter-inch drive designation, referring to socket wrench drives that use a 1/4-inch square drive. This size is contrasted with larger drives such as 3/8 inch and 1/2 inch drives.

While 1/4 inch is a precise measurement in some contexts, actual tolerances vary by material, manufacturing processes, and standards. In mixed measurement environments (for example, metric countries), 1/4 inch is approximately 6.35 millimeters, and engineers may specify exact tolerances in metric units.