Metric Tap Drill Sizes

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

Metric Fine SizesMetric Coarse Sizes
    
Tap Size (mm)Drill Size (mm)Tap Size (mm)Drill Size (mm)
    
4 x 0.353.61 x 0.250.75
4 x 0.53.51.1 x 0.250.85
5 x 0.54.51.2 x .250.95
6 x 0.55.51.4 x 0.31.1
6 x 0.755.251.6 x 0.351.25
7 x 0.756.251.7 x 0.351.3
8 x 0.571.8 x 0.351.45
8 x 0.757.252 x 0.41.6
8 x 172.2 x 0.451.75
9 x 182.5 x 0.452
10 x 0.759.253 x 0.52.5
10 x 193.5 x 0.62.9
10 x 1.258.84 x 0.73.3
11 x 1104.5 x 0.753.7
12 x 0.7511.255 x 0.84.2
12 x 1116 x 15
12 x 1.510.57 x 16
14 x 1138 x 1.256.8
14 x1.2512.89 x 1.257.8
14 x 1.512.510 x 1.58.5
16 x 11511 x 1.59.5
16 x 1.514.512 x 1.7510.2
18 x 11714 x 212
18 x 21616 x 214
20 x 11918 x 2.515.5
20 x 1.518.520 x 2.517.5
20 x 21822 x 2.519.5
22 x 12124 x 321
22 x 1.520.527 x 324
22 x 22030 x 3.526.5
24 x 1.522.533 x 3.529.5
24 x 22236 x 432
26 x 1.524.539 x 435
27 x 1.525.5  
27 x 225  
28 x 1.526.5  
30 x 1.528.5  
30 x 228  
33 x 231  
36 x 333  
39 x 336  
    
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.

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