Fasteners are not universal. A bolt made to German (DIN) dimensions will often look similar to an American (ANSI) bolt but differ in thread pitch, head size and tolerances. Specifying the wrong system means parts that will not fit or will not meet your local code. This guide is based on the standards we manufacture to.

Two Systems, Two Markets

The split is largely geographic:

  • DIN (Deutsches Institut für Normung) — the European / metric system. Used across Europe, the Middle East and much of Africa and Asia. Threads are specified in millimetres (M-series).
  • ANSI (American National Standards Institute) — the inch system. Dominant in North America and common across South America. Threads are specified in inches (UNC / UNF).

Both systems also cover pipe threads such as G (metric/BSP parallel) and NPT (National Pipe Taper) for plumbing and fluid connections.

Side-by-Side Comparison

Aspect DIN (Metric) ANSI (Inch)
Thread system Metric M-thread — e.g. M6, M8, M10, M12 (pitch in mm) Inch UNC / UNF — e.g. 1/4"-20, 5/16"-18 (TPI)
Common hex bolt DIN 933 (full thread) / DIN 931 (partial thread) ANSI B18.2.1 hex / heavy hex bolt
Dimension notation Diameter × length in mm (e.g. M10 × 80) Diameter in inches × length in inches (e.g. 3/8" × 3")
Flange bolt example DIN 6921 ANSI B18.2.1 flange hex
Preferred markets Europe, Middle East, Africa North America, South America

Procurement Advice: Let the Market Decide

The simplest rule is to follow the standard your market already uses:

  • Europe / Middle East / Africa → specify DIN (metric M-thread). See our market pages for Africa and the broader markets we serve.
  • North America / South America → specify ANSI (inch UNC/UNF). See South America for an ANSI/UNC preference example.
  • India / Russia → mixed: India commonly uses IS / DIN / ANSI (see India), Russia uses GOST / DIN (see Russia). GOST and IS coverage is available on request — available on request.

How We Support Both Standards

Donghuang Hardware manufactures to the major international systems, so you do not need multiple vendors:

  • Produced to DIN, ANSI, GB and JIS standards.
  • Both metric (M) and inch (UNC/UNF) threads supported across our bolt, nut and screw ranges.
  • Custom manufacturing for non-standard sizes and drawings, with in-house tooling.
  • Free samples so you can verify fit against your existing parts before ordering.
Tell us your standard when inquiring. Include DIN or ANSI (and the exact standard number if known) in your request so we quote the correct thread, head size and tolerances. Browse our bolts range to see typical DIN / ANSI part types.

Not sure which standard your project needs? Contact our team with your application and market — we will confirm the right specification.