Tap drill center
Tap Drill Charts and Calculator
Start with the exact thread and tapping method. Reviewed lookups lead; formulas are labeled as estimates; unsupported combinations stay unavailable.
Reference library
Focused pages with a clear owner
Each URL answers a distinct question. ThreadSizeGuide avoids automatically generating thin pages for every possible size.
Inch Tap Drill Chart for UNC and UNF Threads
Reviewed cut-tap drill sizes for common UNC and UNF threads, with decimal equivalents, source context and selection limitations.
Read reference →Tap drill referenceMetric Tap Drill Chart for Common Coarse Threads
Reviewed metric cut-tap drill recommendations for M3 through M12, with pitch, decimal-inch context and limitations.
Read reference →Pipe thread boundaryNPT and BSP Tap Drill Selection: What Changes
Understand why NPT and BSP tap drill selection needs standard-specific tables, taper awareness and proper gauges instead of straight-thread formulas.
Read reference →Size reference1/4-20 Tap Drill Size
The reviewed 1/4-20 UNC cut-tap drill size, decimal and metric equivalents, calculation cross-check and practical limitations.
Read reference →Size reference10-32 Tap Drill Size
The reviewed #10-32 UNF cut-tap drill size with decimal equivalent, method and practical limitations.
Read reference →Size reference3/8-16 Tap Drill Size
The reviewed 3/8-16 UNC cut-tap drill size, equivalents and selection notes.
Read reference →Size referenceM6 Tap Drill Size
The reviewed M6 × 1.0 cut-tap drill size with inch equivalent, method and pitch warning.
Read reference →Pipe-thread source comparison1/8-27 NPT Tap Drill Size
Compare published 1/8-27 NPT tap-drill recommendations and understand why reaming context prevents one universal answer.
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