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Metric Tap Drill Sizes

Find the correct drill size prior to using a thread tap. Suitable for Masonry, Wood and Metal Balustrade, Trellis and Catenary Systems

Metric Fine Sizes		Metric Coarse Sizes

Tap Size (mm)	Drill Size (mm)	Tap Size (mm)	Drill Size (mm)

4 x 0.35	3.6	1 x 0.25	0.75
4 x 0.5	3.5	1.1 x 0.25	0.85
5 x 0.5	4.5	1.2 x .25	0.95
6 x 0.5	5.5	1.4 x 0.3	1.1
6 x 0.75	5.25	1.6 x 0.35	1.25
7 x 0.75	6.25	1.7 x 0.35	1.3
8 x 0.5	7	1.8 x 0.35	1.45
8 x 0.75	7.25	2 x 0.4	1.6
8 x 1	7	2.2 x 0.45	1.75
9 x 1	8	2.5 x 0.45	2
10 x 0.75	9.25	3 x 0.5	2.5
10 x 1	9	3.5 x 0.6	2.9
10 x 1.25	8.8	4 x 0.7	3.3
11 x 1	10	4.5 x 0.75	3.7
12 x 0.75	11.25	5 x 0.8	4.2
12 x 1	11	6 x 1	5
12 x 1.5	10.5	7 x 1	6
14 x 1	13	8 x 1.25	6.8
14 x1.25	12.8	9 x 1.25	7.8
14 x 1.5	12.5	10 x 1.5	8.5
16 x 1	15	11 x 1.5	9.5
16 x 1.5	14.5	12 x 1.75	10.2
18 x 1	17	14 x 2	12
18 x 2	16	16 x 2	14
20 x 1	19	18 x 2.5	15.5
20 x 1.5	18.5	20 x 2.5	17.5
20 x 2	18	22 x 2.5	19.5
22 x 1	21	24 x 3	21
22 x 1.5	20.5	27 x 3	24
22 x 2	20	30 x 3.5	26.5
24 x 1.5	22.5	33 x 3.5	29.5
24 x 2	22	36 x 4	32
26 x 1.5	24.5	39 x 4	35
27 x 1.5	25.5
27 x 2	25
28 x 1.5	26.5
30 x 1.5	28.5
30 x 2	28
33 x 2	31
36 x 3	33
39 x 3	36

Tip: To calculate the tap drill size for metric threads the diameter of
thread minus the thread pitch will give you the required tap drill size.
e.g. for M6 x 1 thread size 6 - 1 = 5mm so use a 5mm drill.