Nut Bolt Size Chart – Metric & Inch Dimensions, Thread Types & Application Guide
Nut Bolt Size Chart – Metric & Inch Dimensions, Thread Types & Application Guide (2025)
Introduction
Choosing the correct nut and bolt size is crucial for any mechanical, structural, or industrial application. In this guide, we present a full nut bolt size chart in mm and inches, including M4, M6, M8, M10, M12, and more. You’ll also find thread types, fit classes, and usage areas for each size category.
Standard Metric Nut Bolt Size Chart (mm)
| Size (M) | Thread Pitch (mm) | Head Size (Across Flats) | Common Lengths (mm) | Applications |
|---|---|---|---|---|
| M2 | 0.4 | 4 mm | 6–20 | Electronics, circuit boards |
| M3 | 0.5 | 5.5 mm | 6–50 | Plastic enclosures, gadgets |
| M4 | 0.7 | 7 mm | 8–100 | Furniture, small appliances |
| M5 | 0.8 | 8 mm | 10–100 | Tools, mounting brackets |
| M6 | 1.0 | 10 mm | 10–120 | Home hardware, steel joints |
| M8 | 1.25 | 13 mm | 16–150 | Automobile parts, machinery |
| M10 | 1.5 | 17 mm | 20–200 | Construction, heavy-duty frames |
| M12 | 1.75 | 19 mm | 25–250 | Structural, motor mounts |
Note: For longer bolt requirements, M6 to M12 sizes are often classified under long nut bolts.
Nut Bolt Size Chart in Inches (Imperial)
| Size (Inch) | Thread Type | Wrench Size (inch) | Common Use |
|---|---|---|---|
| 1/8" | 32 TPI (Unified) | 0.3125" | Light fittings, sensors |
| 1/4" | 20 TPI | 7/16" | Cabinetry, furniture |
| 3/8" | 16 TPI | 9/16" | HVAC systems |
| 1/2" | 13 TPI | 3/4" | Plumbing, steel brackets |
| 5/8" | 11 TPI | 15/16" | Heavy load fastenings |
Bolt Lengths and Diameter Reference
Bolt length is measured from the underside of the head to the end of the shank. Below are standard size groups:
- Small Nut Bolts: 2mm to 5mm – used in electronics, toys, and light-duty fixtures.
- Medium Nut Bolts: 6mm to 10mm – used in furniture, household appliances, and enclosures.
- Large Nut Bolts: 12mm and above – used in construction, flanges, motors, and industrial machines.
Thread Pitch Chart for Metric Bolts
| Metric Size | Standard Pitch (mm) | Fine Pitch (mm) |
|---|---|---|
| M6 | 1.0 | 0.75 / 0.5 |
| M8 | 1.25 | 1.0 / 0.75 |
| M10 | 1.5 | 1.25 / 1.0 |
| M12 | 1.75 | 1.5 / 1.25 |
Application of Nut Bolt Sizes in Industry
- 2mm–3mm: Circuit boards, toys, clocks
- 4mm–6mm: Furniture, door handles, panels
- 8mm–10mm: Fan mounts, steel furniture, auto parts
- 12mm+: Concrete frames, flange joints, machines
Download PDF – Nut Bolt Size Chart
Looking for a print-ready size guide?Download our full Nut Bolt Size Chart PDF including metric, inch, and pitch references for quick access.
FAQs – Nut Bolt Size Reference
- Q. What is the difference between M8 and 8mm bolt?
- They refer to the same size. M8 indicates metric thread diameter of 8mm.
- Q. How do I measure a bolt size?
- Measure the shank diameter (not including threads) and the length from under the head to the tip.
- Q. Which size is best for motor mounts?
- M10 to M12 bolts with fine thread and washers are ideal for motor and engine applications.
- Q. Are long nut bolts different from threaded rods?
- Yes. Long nut bolts have a fixed head; threaded rods are headless and used with two nuts.
Related Pages
- Types of Nuts and Bolts – Wing, T, Flange, and Locking Types
- Nut Bolt Manufacturers in India – Verified Exporters
- Nut Bolt Price List Per KG – SS, GI, MS Fasteners (2025)
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