Standard NPT Tap Drill Sizes Chart

StandardNPTTapDrillSizesChart.pdf

Standard NPT Tap Drill Sizes

NPT Size Tap Drill Size (in.) Decimal Equivalent (in.)
1/16 – 27 “C” 0.242
1/8 – 27 “Q” 0.332
1/4 – 18 7/16 0.438
3/8 – 18 9/16 0.562
1/2 – 14 45/64 0.703
3/4 – 14 29/32 0.906
1.0 – 11 – 1/2 1-9/64 1.141
1 – 1/4 – 11 – 1/2 1-31/64 1.484
1 – 1/2 – 11 – 1/2 1-23/32 1.719
2.0 – 11 – 1/2 2-3/16 2.188
2 – 1/2 – 8 2-39/64 2.609
3.0 – 8 3-15/64 3.234

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