Hex Nut Dimensions Guide: Standard Sizes & Tolerances

Understanding hex nut dimensions is essential when choosing the right nut for your application. As a professional wing nut supplier, XINCHI is glad to share the standard metric and imperial size charts, key international standards like DIN, ANSI, and ISO, and practical tips for selecting the correct hex nut for your project.

Metric Hex Nut Sizes (DIN / ISO Standards)

Metric hex nuts are commonly used in global applications and follow DIN 934 or ISO 4032 standards. Below are typical dimensions for commonly used sizes：

• M4: Width across flats 7 mm, height 3.2 mm

• M5: Width across flats 8 mm, height 4.0 mm

• M6: Width across flats 10 mm, height 5.0 mm

• M8: Width across flats 13 mm, height 6.5 mm

• M10: Width across flats 17 mm, height 8.0 mm

• M12: Width across flats 19 mm, height 10.0 mm

• M16: Width across flats 24 mm, height 13.0 mm

• M20: Width across flats 30 mm, height 16.0 mm

These dimensions ensure compatibility with standard metric bolts and tools. Note that slight variations may occur depending on tolerance grades or nut types.

Imperial Hex Nut Sizes (ANSI Standards)

Imperial (inch-based) hex nuts follow ANSI/ASME B18.2.2 standards and are widely used in the United States and some other markets. Common sizes include:

• 1/4″-20: 20 threads per inch, width across flats 7/16″, height 7/32″

• 5/16″-18: 18 TPI, width 1/2″, height 17/64″

• 3/8″-16: 16 TPI, width 9/16″, height 21/64″

• 1/2″-13: 13 TPI, width 3/4″, height 7/16″

• 5/8″-11: 11 TPI, width 15/16″, height 35/64″

• 3/4″-10: 10 TPI, width 1-1/8″, height 43/64″

These values help ensure proper tool fit and structural performance across a wide range of imperial bolts.

Common Hex Nut Standards 

When selecting hex nuts, different standards apply depending on the region and application. Commonly referenced standards include：

• DIN 934: The standard hex nut in Germany and across Europe

• ISO 4032: The international equivalent of DIN 934

• ANSI/ASME B18.2.2: Covers inch-based hex nuts for North American markets

• DIN 439 / ISO 4035: Specifies thin or jam nuts (low height)

• DIN 6915: Defines high-strength structural hex nuts used in steel structures and heavy-duty applications

Knowing the applicable standard ensures compatibility, especially in regulated or export-focused projects.

How to Choose the Right Hex Nut Size

Selecting the correct hex nut involves more than matching thread size. Consider the following:

Thread Compatibility
Always match the nut’s thread size and pitch with the corresponding bolt or stud.

Load Requirements
For high-stress applications, use heavy-duty or structural nuts (e.g., DIN 6915).

Material & Coating
Choose stainless steel for corrosion resistance, or zinc-plated carbon steel for cost-efficiency.

Dimensional Fit
Ensure the proper wrench size fits your selected width across flats, especially in tight spaces.

Compliance with Standards
For international projects, confirm the required DIN/ISO/ANSI specifications.

Xinchi Fasteners – Your Trusted Hex Nut Supplier

At Xinchi, we offer a complete range of hex nuts in metric and inch sizes, with full compliance to DIN, ISO, and ANSI standards. Whether you’re sourcing for construction, machinery, automotive, or general industrial use, we deliver:

• Precision-manufactured fasteners with tight tolerances
• Various materials including carbon steel, stainless steel, and alloy steel
• Custom coatings and packaging options
• Fast lead times and OEM support

XINCHI is a trustworthy fastener company, especially in furniture nuts. We have a factory,  founded in 2007. We are the designated fastener supplier to“STAPLE”. As a trusted fastener supplier, XINCHI offers a wide range of high-quality fasteners, including nuts, screws, bolts, rivets, and washers. If you would like to learn more about fasteners or are interested in wholesale fasteners, please do not hesitate to contact us. Our experienced and expert service team will reply as soon as possible.

Need Help with Hex Nut Selection?

Contact our technical team for assistance with dimensions, standards, or sample requests. We’re here to help you find the perfect hex nut for your application.