About This Reference Utility

Drill Size Reference is a dedicated technical reference utility built for machinists, fabricators, woodworkers, mechanics, engineers, and DIY makers.

Project Focus

The tool was created to provide instant, zero-clutter access to accurate dimensions across three fundamental workshop operations:

• Standard Drill Bit Sizes: Comparing fractional, metric, number (#80–#1), and letter (A–Z) sizes with exact decimal inch and millimeter equivalents.
• Tap Drill Recommendations: Identifying the correct pre-drilled hole size for Unified (UNC/UNF) and Metric (M) threads before tapping.
• Clearance Hole Dimensions: Choosing appropriate through-hole sizes for standard inch and metric bolts across close, normal, and loose fit classes.

Design Philosophy

• Speed First: Instant client-side search, zero bloated JavaScript libraries, and static pre-rendered HTML for maximum speed.
• Data Integrity: All tables are compiled from verified published standards (ASME and ISO) with explicit source attribution and full transparency.
• Shop Floor Usability: High-contrast tabular numbers, responsive layout for mobile phone screens, clean printable formats, and quick copy-to-clipboard actions.