Metric Tap Drill Chart for Common Coarse Threads

The dataset contains source-backed coarse and fine metric records rather than an automatically generated table of unsupported combinations.

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Metric cutting-tap drill chart

These are manufacturer recommendations for cutting taps. Diameter conversions are display aids; the named drill designation remains the lookup result.

Thread	Pitch	Recommended drill	Diameter	Converted diameter
M3 × 0.5	0.5 mm	2.5 mm	2.5 mm	0.0984 in
M4 × 0.7	0.7 mm	3.3 mm	3.3 mm	0.1299 in
M5 × 0.8	0.8 mm	4.2 mm	4.2 mm	0.1654 in
M6 × 1.0	1 mm	5.0 mm	5.0 mm	0.1969 in
M8 × 1.25	1.25 mm	6.7 mm	6.7 mm	0.2638 in
M10 × 1.5	1.5 mm	8.5 mm	8.5 mm	0.3346 in
M12 × 1.75	1.75 mm	10.2 mm	10.2 mm	0.4016 in
M1.6 × 0.35	0.35 mm	1.25 mm	1.25 mm	0.0492 in
M2 × 0.4	0.4 mm	1.6 mm	1.6 mm	0.0630 in
M2.5 × 0.45	0.45 mm	2.05 mm	2.05 mm	0.0807 in
M3.5 × 0.6	0.6 mm	2.9 mm	2.9 mm	0.1142 in
M4.5 × 0.75	0.75 mm	3.7 mm	3.7 mm	0.1457 in
M7 × 1.0	1.0 mm	6.0 mm	6.0 mm	0.2362 in
M8 × 1.0	1.0 mm	7.0 mm	7.0 mm	0.2756 in
M10 × 1.25	1.25 mm	8.7 mm	8.7 mm	0.3425 in
M12 × 1.25	1.25 mm	10.8 mm	10.8 mm	0.4252 in
M14 × 2.0	2.0 mm	12.0 mm	12.0 mm	0.4724 in
M16 × 2.0	2.0 mm	14.0 mm	14.0 mm	0.5512 in
M16 × 1.5	1.5 mm	14.5 mm	14.5 mm	0.5709 in
M18 × 2.5	2.5 mm	15.5 mm	15.5 mm	0.6102 in
M18 × 1.5	1.5 mm	16.5 mm	16.5 mm	0.6496 in
M20 × 2.5	2.5 mm	17.5 mm	17.5 mm	0.6890 in
M20 × 1.5	1.5 mm	18.5 mm	18.5 mm	0.7283 in
M22 × 2.5	2.5 mm	19.5 mm	19.5 mm	0.7677 in
M22 × 1.5	1.5 mm	20.5 mm	20.5 mm	0.8071 in
M24 × 3.0	3.0 mm	21.0 mm	21.0 mm	0.8268 in
M24 × 2.0	2.0 mm	22.0 mm	22.0 mm	0.8661 in

The diameter-minus-pitch rule

For an M6 × 1.0 thread, 6.0 mm minus 1.0 mm gives a 5.0 mm starting drill. This is an approximate cut-tap rule, not a complete tolerance calculation.

Published recommendations can choose the nearest available drill and can differ for a given engagement target. The reviewed M8 × 1.25 record, for example, uses the value shown in the cited maker chart.

Use millimeters throughout the calculation.
Keep the pitch visible; M10 can have several pitches.
Treat forming taps as a separate process.

Coarse and fine metric series

The letter M and nominal diameter do not fully identify a metric thread when multiple pitches exist. Record the pitch on drawings, setup sheets and inspection records whenever ambiguity is possible.

Important limitation
These are general cut-tap references. Hole tolerance, work material, tap style and required thread class remain application decisions.

Technical references

Cle-Line C01112 Tap and Drill Recommendations — Greenfield Industries / Cle-Line. Accessed 2026-11-09.
ISO 261 ISO general purpose metric screw threads — General plan — International Organization for Standardization. Accessed 2026-11-09.

Standards references identify scope and terminology; protected dimensional tables are not reproduced.