Tap Size Drill Size
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M5 x 0.8 4.2mm
M5 x 0.9 4.2mm
M6 x 1 5mm
M6.3 x 1 5.5mm
What is tap drill size formula?
Tap-drill diameter equals nominal diameter minus thread pitch. I quickly calculate proper tap-drill diameters using this simple formula. Tap-drill diameter equals nominal diameter minus thread pitch. For example, drill size for a 3/8-16 thread is 0.375 0.0625 (pitch) = 0.312 in.