Metric Thread Drilling Calculator
Select the metric thread size to calculate the required drilling diameter:–
Thread Size | Pitch (mm) | Major Diameter (mm) | Minor Diameter (mm) |
---|---|---|---|
– | – | – | – |
Metric Thread Drilling Guide
Your go-to chart for finding the right drill diameter for threading
Introduction
For metalworkers, selecting the correct drill bit diameter is essential when preparing to cut metric threads. Drilling the right-sized hole ensures a proper fit for the threaded insert, avoiding thread damage and ensuring the strength and stability of the finished piece. This helpful guide offers an easy-to-use metric thread chart, highlighting the key major and minor diameters for common metric threads.
Why Accurate Hole Sizes Matter
When you’re cutting threads, the diameter of the drilled hole must align with the thread’s specifications. An incorrect hole size can cause threads to be too loose or too tight, leading to poor engagement, thread damage, or weakened joints. Whether you’re working with bolts, nuts, or threaded inserts, understanding and applying the right drill size is a must for precision.
Metric Thread Drilling Chart: Major and Minor Diameters
The chart below outlines the necessary drill bit sizes for various metric threads. The chart includes both the major diameter (the outside diameter of the thread) and the minor diameter (the inner diameter of the thread), which are crucial for determining the correct drill bit for tapping or cutting threads into materials.
Thread Size (M) | Thread Designation | Pitch (mm) | Drill Diameter (mm) | Major Diameter (mm) | Minor Diameter (mm) |
---|---|---|---|---|---|
M1 | M1x0.25 | 0.25 | 0.982 | 0.982 | 0.729 |
M2 | M2x0.4 | 0.4 | 1.981 | 1.981 | 1.567 |
M3 | M3x0.5 | 0.5 | 2.980 | 2.980 | 2.459 |
M4 | M4x0.7 | 0.7 | 3.978 | 3.978 | 3.242 |
M5 | M5x0.8 | 0.8 | 4.976 | 4.976 | 4.134 |
M6 | M6x1 | 1 | 5.974 | 5.974 | 4.917 |
M7 | M7x1 | 1 | 6.974 | 6.974 | 5.917 |
M8 | M8x1.25 | 1.25 | 7.972 | 7.972 | 6.647 |
M9 | M9x1.25 | 1.25 | 8.972 | 8.972 | 7.647 |
M10 | M10x1.5 | 1.5 | 9.968 | 9.968 | 8.376 |
M12 | M12x1.75 | 1.75 | 11.970 | 11.970 | 10.106 |
M14 | M14x2 | 2 | 13.960 | 13.960 | 11.835 |
M16 | M16x2 | 2 | 15.960 | 15.960 | 13.835 |
M18 | M18x2.5 | 2.5 | 17.960 | 17.960 | 15.294 |
M20 | M20x2.5 | 2.5 | 19.960 | 19.960 | 17.294 |
M22 | M22x2.5 | 2.5 | 21.960 | 21.960 | 19.294 |
M24 | M24x3 | 3 | 23.950 | 23.950 | 20.752 |
M27 | M27x3 | 3 | 26.950 | 26.950 | 23.752 |
M30 | M30x3.5 | 3.5 | 29.950 | 29.950 | 26.211 |
M33 | M33x3.5 | 3.5 | 32.970 | 32.970 | 29.211 |
M36 | M36x4 | 4 | 35.940 | 35.940 | 31.670 |
M39 | M39x4 | 4 | 38.940 | 38.940 | 34.670 |
M42 | M42x4.5 | 4.5 | 41.940 | 41.940 | 37.129 |
M45 | M45x4.5 | 4.5 | 44.940 | 44.940 | 40.129 |
M48 | M48x5 | 5 | 47.930 | 47.930 | 42.587 |
M52 | M52x5 | 5 | 51.930 | 51.930 | 46.587 |
M56 | M56x5.5 | 5.5 | 55.930 | 55.930 | 50.046 |
How to Use the Chart
1. Select Thread Size: Find the metric thread size you plan to use (e.g., M6, M8, M10, etc.).
2. Check the Pitch: Determine the pitch, or the distance between threads, which can be found in your specifications.
3. Choose the Correct Drill Bit: Match the thread size and pitch to the chart’s recommended drill bit diameter.
Common Drill Size Mistakes to Avoid
Drilling too large a hole: Drilling a hole that is too large can cause the threads to be weak, making the fastening prone to failure.
Drilling too small a hole: A hole that is too small for the specified diameter will result in poorly formed threads or cause unnecessary stress on your tools.
Additional Threading Tips for Metalworkers
- Use the Right Drill Bit: A standard twist drill bit works well for most applications, but for precise threading, you may also want to use a drill bit designed for tapping.
- Consider Material Type: Harder materials (like steel) may require different drill sizes, as they resist cutting and threading more than softer materials.
- Tapping Drills vs. Through-Hole Drills: If you are tapping a hole, always follow the drill sizes that correspond to the required tapping drill bit. For through-holes, the chart above should suffice.
Conclusion
For successful threading and metalworking projects, knowing the correct drill bit size is crucial. This metric thread drilling guide provides metalworkers with the exact drill diameters needed for various thread sizes, ensuring precise and secure thread cutting every time. Whether you are working on bolts, fasteners, or other metal components, this chart will make your project smoother and more accurate.