Metric Tap Drill Size — Your Quick Guide

tap drill bit

What is a Tap Drill?

In order to make a threaded hole in a material, you need to utilize a tap drill. It is a particular kind of drill bit made with cutting threads into a substance in mind.

The size of the bolt or thread that will be utilized determines the size of the tap drill. The depth and the total number of threads that will be produced depend on the size of the tap drill.

What is the Metric Tap Drill Size?

The metric tap drill size is the size of the drill bit that is used to create the threads in a material. The size of the drill bit is based on the diameter of the bolt or thread that will be used.

Generally, the metric tap drill size is slightly smaller than the bolt or thread so that the threads can be tapped into the material without damaging it.

How to Determine the Metric Tap Drill Size

To determine the metric tap drill size, you will need to know the size of the bolt or thread that will be used. Once you know the size, you can look up the corresponding tap drill size in a chart or calculator. Depending on the material and the application, you may need to use a specific type of drill bit.

Choosing the tap according to hole size requirement

How Do You Calculate Metric Tap Drill Size?

Metric tap drill size is calculated by first knowing the size of the bolt or thread that will be used. Once the size is determined, a chart or calculator can be used to determine the corresponding tap drill size. Depending on the material and the application, special drill bits may be needed.

Metric Tap Drill Size Table

Below is a table on the available tap drill sizes for your reference:

Size of Bolt or Thread (mm) 

Tap Drill Size (mm)

M3

2.5

M4

3.3

M5

4.2
M6

5.0

M8

6.8

M10

8.5
M12

10.2

M14

11.9
M16

13.7

M18

15.4
M20

17.2

M22

19.0
M24

20.7

M27

23.4
M30

26.1

M33

28.9
M36

31.6

M39

34.3
M42

37.0

M45

39.8
M48

42.5

M52

46.2
M56

49.9

M60

53.7
M64

57.4

M68

61.1
M72

64.8

M76

68.6
M80

72 30

M85

76.0
M90

79.8

M95

83.5
M100

87.2

Conclusion

Metric tap drill sizes are an important factor in ensuring that threads are created properly when drilling into materials. Knowing the size of the bolt or thread that will be used is the key to determining the correct tap drill size.

With the right information and tools, it is possible to accurately determine the metric tap drill size for any application.

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