Metric Thread Size Guide: A Helpful Cheat Sheet
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Whether you’re a powder coater, e-coater, anodizer, or plater, understanding thread dimensions is crucial for selecting the right masking solutions. That's why we have created this guide to provide you with a clear and concise reference for metric thread sizes.
Metric vs. Standard Threads: What’s the Difference?
The primary distinction between metric and standard threads lies in how they are specified.
SAE Threads:
• Measured in inches
• Thread pitch indicates the number of threads per inch
• A 1/4-20 thread means the diameter is 1/4 inch and there are 20 threads per inch.
Metric Threads:
• Measured in millimeters
• Thread pitch represents the distance between each thread
• A M18x2.5 thread has a diameter of 18mm and 2.5mm between each thread.
Download our complete Metric Thread Size Guide
Metric thread size guid for external threads (bolts)
| Metric Thread Name | Pitch (mm) | Major Diameter Max (mm) | Major Diameter Min (mm) | Pitch Diameter Max (mm) | Pitch Diameter Min (mm) | Minor Diameter Max (mm) | Minor Diameter Min (mm) |
|---|---|---|---|---|---|---|---|
| M1 | 0.25 | 0.98 | 0.92 | 0.82 | 0.77 | 0.71 | 0.61 |
| M1x0.2 | 0.20 | 0.98 | 0.93 | 0.85 | 0.81 | 0.77 | 0.68 |
| M2 | 0.40 | 1.98 | 1.89 | 1.72 | 1.65 | 1.55 | 1.41 |
| M2x0.25 | 0.25 | 1.98 | 1.92 | 1.82 | 1.76 | 1.71 | 1.61 |
| M3 | 0.50 | 2.98 | 2.87 | 2.66 | 2.58 | 2.44 | 2.27 |
| M3x0.35 | 0.35 | 2.98 | 2.90 | 2.75 | 2.69 | 2.60 | 2.47 |
| M4 | 0.70 | 3.98 | 3.84 | 3.52 | 3.43 | 3.22 | 3.00 |
| M4x0.5 | 0.50 | 3.98 | 3.87 | 3.66 | 3.58 | 3.44 | 3.27 |
| M5 | 0.80 | 4.98 | 4.83 | 4.46 | 4.36 | 4.11 | 3.87 |
| M5x0.5 | 0.50 | 4.98 | 4.87 | 4.66 | 4.58 | 4.44 | 4.27 |
| M6 | 1.00 | 5.97 | 5.79 | 5.32 | 5.21 | 4.89 | 4.60 |
| M6x0.8 | 0.80 | 5.98 | 5.83 | 5.46 | 5.38 | 5.11 | 4.88 |
| M7 | 1.00 | 6.97 | 6.79 | 6.32 | 6.21 | 5.89 | 5.60 |
| M7x0.75 | 0.75 | 6.98 | 6.84 | 6.49 | 6.39 | 6.17 | 5.93 |
| M8 | 1.25 | 7.97 | 7.76 | 7.16 | 7.04 | 6.62 | 6.27 |
| M8x1 | 1.00 | 7.97 | 7.79 | 7.32 | 7.21 | 6.89 | 6.60 |
| M9x1.25 | 1.25 | 8.97 | 8.76 | 8.16 | 8.04 | 7.62 | 7.27 |
| M10 | 1.50 | 9.97 | 9.73 | 8.99 | 8.86 | 8.34 | 7.94 |
| M10x1.25 | 1.25 | 9.97 | 9.76 | 9.16 | 9.04 | 8.62 | 8.27 |
| M11x1 | 1.00 | 10.97 | 10.79 | 10.32 | 10.21 | 9.89 | 9.60 |
| M12 | 1.75 | 11.97 | 11.70 | 10.83 | 10.68 | 10.07 | 9.60 |
| M12x1.5 | 1.50 | 11.97 | 11.73 | 10.99 | 10.85 | 10.34 | 9.93 |
| M12x1 | 1.00 | 11.97 | 11.79 | 11.32 | 11.21 | 10.89 | 10.59 |
Metric thread size guid for internal threads (nuts)
| Metric Thread Name | Pitch (mm) | Major Diameter Max (mm) | Major Diameter Min (mm) | Pitch Diameter Max (mm) | Pitch Diameter Min (mm) | Minor Diameter Max (mm) | Minor Diameter Min (mm) |
|---|---|---|---|---|---|---|---|
| M1x0.25 | 0.25 | 0.73 | 0.81 | 0.84 | 0.91 | 1.00 | 1.11 |
| M1x0.2 | 0.20 | 0.78 | 0.86 | 0.87 | 0.93 | 1.00 | 1.09 |
| M2x0.4 | 0.40 | 1.57 | 1.68 | 1.74 | 1.83 | 2.00 | 2.15 |
| M2x0.25 | 0.25 | 1.73 | 1.81 | 1.84 | 1.91 | 2.00 | 2.11 |
| M3x0.5 | 0.50 | 2.46 | 2.60 | 2.68 | 2.78 | 3.00 | 3.17 |
| M3x0.35 | 0.35 | 2.62 | 2.72 | 2.77 | 2.86 | 3.00 | 3.14 |
| M4x0.7 | 0.70 | 3.24 | 3.42 | 3.55 | 3.66 | 4.00 | 4.22 |
| M4x0.5 | 0.50 | 3.46 | 3.60 | 3.68 | 3.78 | 4.00 | 4.17 |
| M5x0.8 | 0.80 | 4.13 | 4.33 | 4.48 | 4.61 | 5.00 | 5.24 |
| M5x0.5 | 0.50 | 4.46 | 4.60 | 4.68 | 4.78 | 5.00 | 5.17 |
| M6x1 | 1.00 | 4.92 | 5.15 | 5.35 | 5.50 | 6.00 | 6.29 |
| M6x0.8 | 0.80 | 5.13 | 5.33 | 5.48 | 5.59 | 6.00 | 6.22 |
| M7x1 | 1.00 | 5.92 | 6.15 | 6.35 | 6.50 | 7.00 | 7.29 |
| M8x1.25 | 1.25 | 6.65 | 6.91 | 7.19 | 7.35 | 8.00 | 8.34 |
| M8x1 | 1.00 | 6.92 | 7.15 | 7.35 | 7.50 | 8.00 | 8.29 |
| M9x1.25 | 1.25 | 7.65 | 7.91 | 8.19 | 8.35 | 9.00 | 9.34 |
| M10x1.5 | 1.50 | 8.38 | 8.68 | 9.03 | 9.21 | 10.00 | 10.40 |
| M10x1.25 | 1.25 | 8.65 | 8.91 | 9.19 | 9.35 | 10.00 | 10.34 |
| M11x1.5 | 1.50 | 9.38 | 9.68 | 10.03 | 10.20 | 11.00 | 11.39 |
| M12x1.75 | 1.75 | 10.11 | 10.44 | 10.86 | 11.06 | 12.00 | 12.45 |
| M12x1.5 | 1.50 | 10.38 | 10.68 | 11.03 | 11.22 | 12.00 | 12.41 |
| M12x1.25 | 1.25 | 10.65 | 10.91 | 11.19 | 11.37 | 12.00 | 12.36 |