Product classification
HS code for Hex nuts: 7318.16
Iron or steel, threaded nuts.
Classification of hex nuts under HS 7318.16
Hex nuts are classified under HS code 7318.16, which specifically covers threaded nuts made of iron or steel. This code is part of Chapter 73, which encompasses articles of iron or steel. Heading 7318 covers screws, bolts, nuts, coach screws, screw hooks, rivets, cotters, cotter-pins, washers, and similar articles. The classification is based on the physical characteristics of the item—being an internally threaded fastener designed to mate with a bolt or screw—and the material composition. Hexagonal nuts are the most common variety, but the code applies to various shapes of threaded nuts provided they are made of iron or steel. The classification process involves verifying that the product is threaded; non-threaded fasteners or "nuts" without internal threads would fall under different subheadings such as 7318.29. Furthermore, the material is critical; if the nut is made of copper or aluminum, it would be classified in Chapter 74 or 76, respectively. For 7318.16, the steel can be stainless, alloy, or non-alloy, though specific statistical suffixes may differentiate between these types in certain national tariffs. The presence of a hexagonal shape is the industry standard for these fasteners, facilitating the use of wrenches and sockets for tightening.
- Covers
- Standard hexagonal nuts
- Lock nuts (nyloc nuts)
- Heavy hex nuts
- Hex jam nuts
- Flange hex nuts
- Slotted hex nuts and castle nuts
- Also under 7318.16
- Nord-Lock washers (used with nuts)
- Fastenal hex nuts
- Würth self-locking nuts
- Böllhoff rivet nuts
Codes often confused with 7318.16
Common mistake. Hex nuts are often confused with HS code 7318.15, which covers bolts and screws. While they are used together, nuts are distinct as the female-threaded component. Another common misclassification occurs with nuts made of non-ferrous metals; for example, brass hex nuts must be classified under 7415.33. Additionally, wing nuts or thumb nuts are sometimes incorrectly placed in general hardware categories, but they belong in 7318.16 if they are threaded and made of steel.
Top exporters and importers of HS 731816 (the code used for hex nuts), 2025
In 2025, the largest exporter of HS 731816 (the code used for hex nuts) in UN Comtrade data was China, with 20% of world exports; the largest importer in UN Comtrade data was the United States, with 17% of world imports. Countries that did not report 2025 data are estimated from partner records, which can understate them.
Figures cover everything classified under HS 731816, not only hex nuts.
Top exporters 2025 · share of world exports
- 1 China $1.7B 20% of world exports
- 2 Taiwan* ~$1.2B 15% of world exports · partner records ↗
- 3 United States $1.2B 14% of world exports
World total: $8.3B Reported figures on UN Comtrade ↗
Top importers 2025 · share of world imports
- 1 United States $1.4B 17% of world imports
- 2 Germany $777M 9.7% of world imports
- 3 Mexico $492M 6.1% of world imports
World total: $8.0B Reported figures on UN Comtrade ↗
How these figures are built
109 countries reported 2025 trade to UN Comtrade in HS 2022, and their own totals are used. Countries marked * did not, so their figures add up what other countries recorded trading with them, and their exports are valued at buyers' CIF prices. Those estimates miss trade with other non-reporting countries, so they can be low, and a non-reporting country can rank higher than shown or be missing from the list. World totals add both and leave out trade between two non-reporting countries. UN Comtrade records Taiwan as "Other Asia, not elsewhere specified". Saudi Arabia's exports under that code are left out: they are far too large to be trade with Taiwan, so mostly undisclosed partners. Figures are in current US dollars; reported imports are mostly valued CIF and exports FOB, and exports include re-exports. The UN Comtrade links show the underlying records; they can also list a few reporters left out here (regional groups and older HS editions).
Source: UN Comtrade (United Nations Statistics Division), 2025 annual data.
Brazil NCM code for hex nuts
Brazil classifies hex nuts under NCM 7318.16.00: HS 7318.16 with 00 added.
Source: Siscomex NCM table, updated Oct 2026. The Portuguese text on each NCM page is the official one.
EU Regulatory Requirements
This product falls under the Carbon Border Adjustment Mechanism (CBAM). Importers to the EU must declare embedded carbon emissions and purchase CBAM certificates.
Questions about hex nuts
What is the HS code for Hex nuts?
The HS code for Hex nuts is 731816 (Iron or steel; threaded nuts).
How do I classify Hex nuts for customs?
Hex nuts is classified under HS code 731816 — Iron or steel; threaded nuts. This is a 6-digit subheading level code.
What is the HS code for stainless steel hex nuts?
Stainless steel hex nuts are classified under HS code 7318.16. While the 6-digit code is the same as carbon steel nuts, the 8 or 10-digit code in many countries will specify the stainless steel material.
Does this code include nuts with nylon inserts?
Yes, hex nuts with nylon locking inserts (nyloc nuts) are classified under 7318.16 because the essential character of the item is the threaded steel nut.
Which countries are the top exporters of hex nuts (HS 731816)?
In 2025, the top exporters of HS 731816 (the code used for hex nuts) in UN Comtrade data were China ($1.7B, 20% of world exports), Taiwan (about $1.2B) and the United States ($1.2B). World exports came to about $8.3B, adding countries' reported figures and partner-based estimates for those that did not report (UN Comtrade data). Countries that did not report 2025 data are estimated from partner records, which can understate them.
Which countries are the top importers of hex nuts (HS 731816)?
In 2025, the top importers of HS 731816 (the code used for hex nuts) in UN Comtrade data were the United States ($1.4B, 17% of world imports), Germany ($777M) and Mexico ($492M). World imports came to about $8.0B, adding countries' reported figures and partner-based estimates for those that did not report (UN Comtrade data). Countries that did not report 2025 data are estimated from partner records, which can understate them.
Is the HS code for Hex nuts the same in all countries?
The base HS code 731816 for Hex nuts is internationally standardized for the first 6 digits across 200+ countries. Individual countries may add additional digits for national tariff lines and specific classifications.
What is the NCM code for hex nuts in Brazil?
In Brazil, hex nuts (HS 731816) is classified under NCM 7318.16.00.