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العربية A metric fastener size chart helps procurement and engineering teams speak the same language. It reduces wrong RFQs, wrong thread matching, and last-minute assembly problems.
In metric fasteners, size is usually written as M + nominal diameter × pitch × length. For example, M12 × 1.75 × 80 means a 12 mm nominal diameter, 1.75 mm thread pitch, and 80 mm length.
For buyers, the key is not only the “M size.” Pitch, length, grade, coating, and matching nuts or washers must also be confirmed.
Basic Metric Fastener Size Chart
Common Metric Sizes and Coarse Pitches
| Metric Size | Common Coarse Pitch | Typical Industrial Use |
|---|---|---|
| M4 | 0.7 mm | Small covers, light brackets |
| M5 | 0.8 mm | Electronics, light machinery |
| M6 | 1.0 mm | Panels, brackets, general assembly |
| M8 | 1.25 mm | Equipment frames, supports |
| M10 | 1.5 mm | Machinery, construction hardware |
| M12 | 1.75 mm | Steel frames, base plates |
| M16 | 2.0 mm | Heavy equipment, structural joints |
| M20 | 2.5 mm | Large machinery, anchors |
| M24 | 3.0 mm | Heavy-duty structures and foundations |
This chart is a starting point. Final selection should follow the drawing, project standard, or equipment manual.
For common catalog items, review standard fasteners and confirm whether the product follows DIN, ISO, ASTM, or a project drawing.
What Procurement Teams Should Confirm
Size Alone Is Not Enough
A purchase request that says “M12 bolt” is incomplete. It can still lead to the wrong product.
Confirm:
- Product type: bolt, screw, nut, washer, stud, or anchor
- Diameter and length
- Thread pitch: coarse or fine
- Thread length: full thread or partial thread
- Grade: 4.8, 8.8, 10.9, 12.9, A2-70, etc.
- Surface finish: plain, zinc, HDG, zinc flake, black, stainless
- Matching nuts and washers
For bolt sourcing, review bolt products. For washer matching, check washer products.
Engineering Checks Before Approval
Match the Size to the Application
Engineering teams should consider load, vibration, corrosion, installation space, and maintenance frequency.
For load-bearing assemblies, high-strength fasteners may be required. For outdoor, marine, or humid environments, compare various coated fasteners or stainless options.
If the part has special head shape, long thread, shoulder diameter, or non-standard length, use custom non-standard fasteners and provide a drawing.
Final Advice
A metric fastener size chart is useful, but it should not replace a complete specification. Good purchasing data includes size, pitch, length, standard, grade, coating, matching parts, and application condition.
For broader sourcing, review the full fastener products range before finalizing the RFQ.