Buyer Guide
Hex nuts are among the most widely used fasteners in mechanical assembly and structural applications. DIN 934 (also referred to as ISO 4032 for international projects) defines the standard dimensions for metric hex nuts from M1.6 up to M39. This guide covers the most commonly sourced range M3 through M24, giving buyers the thread pitch, width across flats, width across corners, and height they need to prepare accurate RFQs.
Understanding DIN 934 Dimensions
The three critical measurements for a hex nut are width across flats (AF), which determines the wrench or socket size needed; width across corners, which affects clearance in counterbored or recessed holes; and height, which influences thread engagement and load capacity. The dimension table above gives these values for each common size.
Width across flats is the most practical measurement for sourcing. An M8 hex nut has a 13 mm AF, an M10 has 16 mm AF, and an M12 has 18 mm AF. These dimensions are standardized and interchangeable between DIN 934 and ISO 4032 for most applications.
Thread Pitch and Tolerances
Coarse thread is standard for DIN 934 hex nuts across all sizes. Thread tolerance class 6H is typical. Fine thread variants exist for some sizes but are less common in general sourcing. Always confirm the required thread pitch with the mating bolt or stud.
Material and Finish Selection
Stainless steel A2 (304) covers most general corrosion-resistant requirements. For marine, chemical processing, or high-chloride environments, stainless steel A4 (316) provides improved pitting resistance. Carbon steel nuts are available in plain finish, zinc-plated, hot-dip galvanized, and other coatings based on the application environment.
Property Classes and Bolt Matching
Each hex nut is manufactured to a property class that defines its proof load and tensile strength. Using the correct nut class with the matching bolt grade prevents thread stripping and ensures the assembly can reach its intended preload.
RFQ Checklist for Hex Nuts
When requesting a quotation for DIN 934 hex nuts, include: size and thread pitch, quantity, material and grade, finish or coating, property class, packing requirements, destination and Incoterms, and any certificate requirements. A complete RFQ helps suppliers quote accurately on the first response.
FAQ
Questions buyers usually ask next.
What is the difference between DIN 934 and ISO 4032 hex nuts?
DIN 934 and ISO 4032 are technically equivalent for most metric sizes. ISO 4032 is the international standard preferred for new designs. DIN 934 is the older German standard still widely referenced in existing drawings.
What nut class should I use for grade 8.8 bolts?
Use class 8 nuts with grade 8.8 bolts. For grade 10.9 bolts, use class 10 nuts. Matching the nut class ensures the intended load capacity.
What is the standard thread pitch for M8, M10, and M12 hex nuts?
M8 uses 1.25 mm pitch, M10 uses 1.5 mm pitch, and M12 uses 1.75 mm pitch for coarse thread.
What materials are DIN 934 hex nuts available in?
Common materials include stainless steel A2 (304), A4 (316) for marine environments, carbon steel with zinc plating for indoor use, and plain carbon steel for heavy-duty applications.
How do I measure a hex nut to confirm the size?
Measure width across flats (AF) using a caliper. Confirm thread pitch with a thread gauge. Compare against the standard dimension table.