NAICS Manufacturing Codes (31-33) – Hierarchy, Definitions & Risk Control
Manufacturing in NAICS is primarily captured under Sectors 31–33. These sectors include establishments that transform materials, substances, or components into new products through mechanical, physical, or chemical processes—including assembly operations when they result in a new product.
The most reliable way to classify manufacturing is to focus on process + production activity (how a product is made), then confirm the definition and exclusions at the 6-digit level using the NAICS Code Lookup Directory. For deeper reference context, see the NAICS Classification & Reference Center.
What counts as manufacturing under NAICS (31–33)
NAICS places an establishment in manufacturing when its primary activity is the transformation of inputs into new outputs. This can include:
Typical manufacturing activities
- Physical or chemical transformation of materials into new products
- Fabrication and forming operations
- Processing and refining (when producing a new product)
- Assembly of parts into a new product (when the output is a distinct manufactured good)
Best-practice verification
- Start with the 6-digit definition for the candidate code
- Confirm included vs excluded activities before finalizing
- Document a short internal note for repeatability and audits
For boundary interpretation guidance, see NAICS Included vs Excluded Activities.
Process vs. product: how NAICS decides boundaries Core rule
Key principle: NAICS manufacturing classification is based on how products are made (process and inputs), not only what the final product looks like or who it’s sold to. This is why products made through similar production processes are often grouped within the same sector.
Tie-breaker rule (when it’s ambiguous): classify based on the activity that accounts for the largest share of production costs or value added.
Critical standard: the establishment rule Data governance
Most common source of discrepancies: NAICS codes are assigned at the establishment level (a single physical location or operating unit), not necessarily at the company/enterprise level.
- A multi-location company may have multiple NAICS codes across plants, warehouses, and administrative units.
- Manufacturing plants are typically coded by their primary production activity, even when the company sells many product lines overall.
- Maintaining establishment-level codes improves comparability across datasets and reduces audit issues in procurement and reporting workflows.
Manufacturing sectors 31, 32, and 33
Manufacturing is grouped into three NAICS sectors. Use the hierarchy pages below to narrow by subsector, industry group, and 6-digit definition.
NAICS 32
Paper, printing, petroleum/coal, chemicals, plastics/rubber, and nonmetallic minerals.
NAICS 33
Primary metals, fabricated metal, machinery, computers/electronics, electrical equipment, transportation equipment, furniture, and miscellaneous manufacturing.
Risk control: manufacturing vs wholesale vs repair Most common audit failure
Many “near-miss” classifications occur when an establishment looks like manufacturing but is primarily wholesale distribution, installation, or repair. Use this decision table to avoid category mismatch.
| Activity type | Usually manufacturing (31–33) when… | Usually NOT manufacturing when… |
|---|---|---|
| Wholesale vs manufacturing | The establishment transforms inputs into new products (fabrication/processing/assembly into a new manufactured output). | The establishment primarily resells goods with limited or no transformation (distribution and sales focus). |
| Repair & maintenance | Work results in a newly manufactured output (new product manufactured from inputs), not just restoring function. | The primary output is repairing/servicing existing products (restoring, maintaining, refurbishing) rather than producing a new product. |
| Installation & field work | Manufacturing occurs at the establishment (plant/facility) and installation is incidental or handled elsewhere. | The establishment primarily performs on-site installation or construction-like work rather than manufacturing output. |
| Assembly-only operations | Assembly produces a distinct product and is the primary output of the establishment. | Assembly is minor packaging/kitting or value-added distribution that does not produce a new manufactured product. |
For program and compliance contexts where NAICS classification affects eligibility, see How NAICS Is Used for Government Programs & Compliance.
Need to find the most defensible manufacturing NAICS code?
Use the directory to confirm the 6-digit definition and exclusions for your primary production activity. If your business has multiple plants or operating units, validate at the establishment level for consistency.
FAQ
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What NAICS codes are considered manufacturing?
Manufacturing is primarily covered under NAICS Sectors 31–33. The correct code depends on your establishment’s primary production activity and should be verified at the 6-digit definition level. -
Does NAICS classify manufacturers by product or by process?
Primarily by process and inputs (how something is made). When the classification is ambiguous, a defensible tie-breaker is to select the activity that represents the largest share of production costs or value added. -
Why do company datasets sometimes show multiple NAICS codes?
NAICS is assigned at the establishment level. A multi-location enterprise may have different NAICS codes across plants, offices, warehouses, and other operating units. -
How do I avoid confusing manufacturing with wholesale or repair?
Confirm whether the establishment’s primary output is a new product created by transformation. If the main activity is resale/distribution or restoring existing products, it is typically not manufacturing.