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Metric Tap Drill Size Chart

ISO metric threads (M-series) – the tap drill for standard coarseness and fine pitch. For metric threads the rule is simply major minus pitch.

Metric tap drill chart

Thread	Pitch	Tap drill	mm	inches
M6×1.0	1	5.0mm	5	0.1969
M8×1.25	1.25	6.8mm	6.8	0.2677
M5×0.8	0.8	4.2mm	4.2	0.1654
M4×0.7	0.7	3.3mm	3.3	0.1299
M3×0.5	0.5	2.5mm	2.5	0.0984
M10×1.5	1.5	8.5mm	8.5	0.3346

The most-searched metric threads – quick access to the sizes machinists look up most: