Thread Pitch UN (Unified National) Thread Pitch Major Dia. UNC (Coarse) UNF (Fine) UNEF (Extra Fine) UN-8 (8 Pitch) #0 0.060 - 80 - - #1 0.073 64 72 - - #2 0.086 56 64 - - #3 0.099 48 56 - - #4 0.112 40 48 - - #5 0.125 40 44 - - #6 0.138 32 40 - - #8 0.164 32 36 - - #10 0.190 24 32 - - #12 0.216 24 28 32 - 1/4 0.250 20 28 32 - 5/16 0.313 18 24 32 - 3/8 0.375 16 24 32 - 7/16 0.438 14 20 28 - 1/2 0.500 13 20 28 - 9/16 0.563 12 18 24 - 5/8 0.625 11 18 24 - 3/4 0.750 10 16 20 - 7/8 0.875 9 14 20 - 1 1.000 8 12 20 8 1 1/8 1.125 7 12 18 8 1 1/4 1.250 7 12 18 8 1 3/8 1.375 6 12 18 8 1 1/2 1.500 6 12 18 8 1 3/4 1.750 5 - 18 8 2 2.000 4.5 - - 8 2 1/4 2.250 4.5 - - 8 2 1/2 2.500 4 - - 8 2 3/4 2.750 4 - - 8 3 3.000 4 - - 8 3 1/4 3.250 4 - - 8 3 1/2 3.500 4 - - 8 3 3/4 3.750 4 - - 8 4 4.000 4 - - 8 NominalSize NPT (National Pipe Thread) and Drill Size Nominal PipeSize(inch) Threads per inch DrillSizeTaper NPT W/Reamer DrilSizeTaper NPT W/O Reamer DrillSizeStraight NPS 1/16" 27 15/64" C 1/4" 1/8" 27 21/64" Q 11/32" 1/4" 18 27/64" 7/16" 7/16" 3/8" 18 9/16" 37/64" 19/32" 1/2" 14 11/16" 45/64" 23/32" 3/4" 14 57/64" 29/32" 15/16" 1" 11.5 1-1/8" 1-9/32" 1-5/32" 1-1/4" 11.5 1-15/32" 1-31/64" 1-1/2" 1-1/2" 11.5 1-23/32" 1-23/32" 1-3/4" 2" 11.5 2-5/32" 2-3/16" 2-3/16" 2-1/2" 8 2-25/32" 2-5/8" 2-5/8" 3" 8 3-9/32" 3-1/4" 3-1/4" 3-1/2" 8 3-3/4" 3-3/4" 3-3/4" 4" 8 4-1/4" 4-1/4" 4-1/4" 5" 8 5-1/4" 5-9/32" 5-5/16" 6" 8 6-1/4" 6-11/32" 6-3/8" Metric (DIN/ISO) Thread Pitch M2 0.40 M2.5 0.45 M3 0.50 M4 0.70 M5 0.80 M6 1.00 M7 1.00 M8 1.25 1.00 M10 1.50 1.25 1.00 M12 1.75 1.50 1.25 M14 2.00 1.50 M16 2.00 M18 2.50 M20 2.50 M22 2.50 M24 3.00 M27 3.00 M30 3.50 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - NominalSize Coarse Fine Extra Fine - 5/8 9/16 7/16 #6 #8 #10 #4 3/4 7/8 1 1/2 1/4 5/16 3/8 #12 Actual Diameter Chart (Inch) M14 M16 M10 M2.5 M3 M4 M2 M18 M20 M22 M12 M6 M7 M8 M5 Actual Diameter Chart (Metric) TM QUICK REFERENCE GUIDE 14 323.262.0259 zalindustrial.com Fastener Catalog 2018.1