Metric Fine Tap Drill Chart

Tap drill sizes for every metric fine thread: the smaller pitches offered alongside each diameter's standard coarse pitch. M8 x 1 instead of M8 x 1.25, M10 x 1.25 instead of M10 x 1.5, and so on. Sort any column, filter by size, and click a row for that size's full page.

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33 sizes

Metric fine tap drill sizes: size, tap drill, decimal inch, millimetres, percent of thread, hard-material drill, form-tap drill, basic minor diameter and pitch.
					tough metal		roll tap
M8 x 1	7 mm	0.2756	7.00	77.0	7.2 mm	61.6	7.6 mm	0.2723	1 mm
M8 x 0.75	7.3 mm	0.2874	7.30	71.9	7.4 mm	61.6	7.7 mm	0.283	0.75 mm
M10 x 1.25	8.8 mm	0.3465	8.80	73.9	9 mm	61.6	9.4 mm	0.3404	1.25 mm
M10 x 1	9 mm	0.3543	9.00	77.0	9.2 mm	61.6	9.6 mm	0.3511	1 mm
M10 x 0.75	9.3 mm	0.3661	9.30	71.9	9.4 mm	61.6	9.7 mm	0.3617	0.75 mm
M12 x 1.5	10.5 mm	0.4134	10.50	77.0	10.8 mm	61.6	11.3 mm	0.4085	1.5 mm
M12 x 1.25	10.8 mm	0.4252	10.80	73.9	11 mm	61.6	11.4 mm	0.4192	1.25 mm
M12 x 1	11 mm	0.4331	11.00	77.0	11.2 mm	61.6	11.6 mm	0.4298	1 mm
M14 x 1.5	12.5 mm	0.4921	12.50	77.0	12.8 mm	61.6	13.3 mm	0.4872	1.5 mm
M14 x 1.25	12.8 mm	0.5039	12.80	73.9	13 mm	61.6	13.4 mm	0.4979	1.25 mm
M16 x 1.5	14.5 mm	0.5709	14.50	77.0	14.8 mm	61.6	15.3 mm	0.566	1.5 mm
M16 x 1	15 mm	0.5906	15.00	77.0	15.2 mm	61.6	15.6 mm	0.5873	1 mm
M18 x 2	16 mm	0.6299	16.00	77.0	16.4 mm	61.6	17.1 mm	0.6234	2 mm
M18 x 1.5	16.5 mm	0.6496	16.50	77.0	16.8 mm	61.6	17.3 mm	0.6447	1.5 mm
M18 x 1	17 mm	0.6693	17.00	77.0	17.2 mm	61.6	17.6 mm	0.666	1 mm
M20 x 2	18 mm	0.7087	18.00	77.0	18.4 mm	61.6	19.1 mm	0.7022	2 mm
M20 x 1.5	18.5 mm	0.7283	18.50	77.0	18.8 mm	61.6	19.3 mm	0.7235	1.5 mm
M20 x 1	19 mm	0.748	19.00	77.0	19.2 mm	61.6	19.6 mm	0.7448	1 mm
M22 x 2	20 mm	0.7874	20.00	77.0	20.5 mm	57.7	21 mm	0.7809	2 mm
M22 x 1.5	20.5 mm	0.8071	20.50	77.0	21 mm	51.3	21.5 mm	0.8022	1.5 mm
M24 x 2	22 mm	0.8661	22.00	77.0	22.5 mm	57.7	23 mm	0.8596	2 mm
M24 x 1.5	22.5 mm	0.8858	22.50	77.0	23 mm	51.3	23.5 mm	0.8809	1.5 mm
M27 x 2	25 mm	0.9843	25.00	77.0	25.5 mm	57.7	26 mm	0.9778	2 mm
M27 x 1.5	25.5 mm	1.0039	25.50	77.0	26 mm	51.3	26.5 mm	0.9991	1.5 mm
M30 x 2	28 mm	1.1024	28.00	77.0	28.5 mm	57.7	29 mm	1.0959	2 mm
M30 x 1.5	28.5 mm	1.122	28.50	77.0	29 mm	51.3	29.5 mm	1.1172	1.5 mm
M33 x 2	31 mm	1.2205	31.00	77.0	31.5 mm	57.7	32 mm	1.214	2 mm
M36 x 3	33 mm	1.2992	33.00	77.0	33.5 mm	64.2	34.5 mm	1.2894	3 mm
M36 x 2	34 mm	1.3386	34.00	77.0	34.5 mm	57.7	35 mm	1.3321	2 mm
M42 x 3	39 mm	1.5354	39.00	77.0	39.5 mm	64.2	40.5 mm	1.5257	3 mm
M42 x 2	40 mm	1.5748	40.00	77.0	40.5 mm	57.7	41 mm	1.5683	2 mm
M48 x 3	45 mm	1.7717	45.00	77.0	45.5 mm	64.2	46.5 mm	1.7619	3 mm
M48 x 2	46 mm	1.811	46.00	77.0	46.5 mm	57.7	47 mm	1.8045	2 mm

Tap a column heading to sort. Every row links to that size's full page.

Always written out in full

This is the single most useful thing to know about metric fine threads: a bare M8 never means a fine thread. Every diameter has one standard coarse pitch, and that is what the unqualified name refers to. A fine pitch is only a fine pitch when the drawing says M8 x 1 in so many words.

The drills are genuinely different: M8 x 1.25 takes 6.8 mm and M8 x 1 takes 7 mm. Drill the coarse hole for a fine tap and you are cutting a thread far deeper than it should be, with the torque to match.

The rule still works

Drill = diameter − pitch holds just as well on fine pitches as on coarse ones, and gives roughly the same 77% of thread. M10 x 1.25 gives 10 − 1.25 = 8.75 mm, and the chart rounds that to 8.8 mm at 73.9%. The arithmetic is easy; the mistake people make is applying it to the wrong pitch.

Identify before you drill

If you are repairing a thread rather than cutting a new one, work out the pitch first. A metric pitch gauge settles it in seconds. Without one, lay a rule along the thread and count crests over 10 mm: ten crests is 1 mm pitch, eight is 1.25 mm, and so on. Guessing is how good parts get ruined.

Coarse versions of these sizes

Every diameter here also has a coarse pitch, listed on the metric coarse chart. Each size's own page shows the other pitches at that diameter side by side with their drills, which is the quickest way to check you have the right one.

Frequently asked questions

What is a metric fine thread?

A metric thread with a smaller pitch than the standard coarse one at that diameter. M8 x 1.25 is coarse; M8 x 1 is fine. A fine pitch is always written out in full, because a bare M8 means the coarse version.

What is the tap drill for M8 x 1?

7 mm, which leaves 77.0% of thread. The coarse M8 x 1.25 takes 6.8 mm instead, so check which one you have before drilling.

How do I tell a fine metric thread from a coarse one?

Use a pitch gauge, or measure the length of ten threads and divide by ten. The difference between 1.25 mm and 1 mm is easy to miss by eye on a single thread and obvious over ten.

When should I use a metric fine thread?

Thin-walled parts, short thread engagement, fine adjustment, and hard material. They are common on hydraulic fittings, automotive components and anything with a locknut that needs to stay put. For general assembly, the coarse pitch is more forgiving.

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