NAICS code for manufacturing: sector 31-33 and how to find your six-digit code

This page is for manufacturers filling in a NAICS or SIC field (SAM.gov, a loan or grant application, an insurer, a state tax incentive) and for sellers building a list of manufacturers. It explains the sector code, the subsectors, how to land on the right six-digit code and how many businesses sit in each part of the sector.

The NAICS code for manufacturing is 31-33

Manufacturing is the only NAICS sector with three two-digit prefixes, because it's too big for one. The Census Bureau's definition: establishments engaged in the mechanical, physical or chemical transformation of materials, substances or components into new products. Assembling component parts counts too, unless the assembly is construction work.

A plant that owns its materials and pays another plant to process them is still a manufacturer, and so is the contract plant doing the processing. Workshops that make goods by hand, and shops that sell what they make on the premises (bakeries, candy stores, custom tailors), can also be manufacturing.

The 21 manufacturing subsectors

Source: County Business Patterns 2023, establishments with paid employees.

How to find your six-digit code

1. List your products by revenue. The NAICS manual classifies an establishment by its principal product, measured in practice by revenue or shipments.
2. Find the subsector by process and material, not by the customer. A shop that mills aluminum brackets to a car maker's drawings on a job basis is 332710 Machine Shops, not a motor vehicle parts code in 336.
3. Pick the six-digit industry in that subsector with the NAICS code lookup, and read its cross-references before you settle.
4. Check your code didn't change in 2022. Sixteen manufacturing codes changed, mostly mergers: car and light truck makers moved from 336111 and 336112 to 336110, and battery makers from 335911 and 335912 to 335910.

The NAICS manual settles the common boundary cases:

Machine shops have more edge cases than most; the NAICS code for a machine shop page covers them.

SIC codes for manufacturers

In the 1987 SIC, manufacturing is Division D: Major Groups 20 to 39, holding 459 four-digit industries from 2011 to 3999. The Census concordance maps most major groups onto one or two NAICS subsectors:

A few SIC codes outside Division D became NAICS manufacturing codes: Retail Bakeries (SIC 5461) partly to 311811, Dental Laboratories (SIC 8072) to 339116, and Tire Retreading and Repair Shops (SIC 7534) partly to 326212. One SIC code can split across several NAICS codes, and the reverse, so check the concordance for your exact code.

How many US manufacturers there are

County Business Patterns 2023 counts 284,452 manufacturing establishments with 12,335,234 employees and $902.96 billion in annual payroll. It counts locations with paid employees (a company with four plants is four establishments) and leaves out one-person shops with no payroll. The 2023 data use 2017 NAICS codes.

The states with the most manufacturing establishments are California (35,300), Texas (21,034), Florida (14,341), New York (13,837) and Ohio (13,307). Manufacturing establishments average 43 employees, against 17 across all industries in CBP, so even a mid-sized plant has separate purchasing, maintenance, quality and operations people to reach.

SBA size standards for manufacturing

Unlike most service codes, manufacturing size standards count employees, averaged over the last 24 completed months, with part-time staff counted the same as full-time. In the SBA's table effective March 17, 2023, they range from 500 to 1,500:

If you sell products you didn't make on a small business set-aside, the nonmanufacturer rule applies instead: no more than 500 employees, primarily in wholesale or retail, supplying the product of a small US manufacturer.

Where the code gets used, and what a wrong one costs

• Federal contracts. The contracting officer assigns one NAICS code to each solicitation, and you must be under that code's size standard. A plant registered only under a wholesale code won't come up when a contracting officer searches SAM.gov by a manufacturing code, and claiming small status you don't have invites a size protest.
• Tax returns. Schedule C uses grouped codes, such as 332000 for all fabricated metal product manufacturing. That's a tax code, not a valid NAICS code for SAM.gov.
• Loans, incentives and insurance. Lenders, insurers and state incentive programs often ask for a NAICS code. Use the same code everywhere, and the one that matches what the plant actually does, because that's what an underwriter or auditor will compare it with.

Finding manufacturing companies

Public manufacturers file under SIC codes 2000 to 3999 on EDGAR, and the SEC's search takes one code at a time: for example, the EDGAR list for SIC 3714, motor vehicle parts. The largest by revenue in their latest 10-K:

Company revenue includes non-manufacturing lines (Apple's services, GM's financing arm), and each company runs many establishments across several codes. For a ranked list, see the largest manufacturing companies; for how plants buy, see the manufacturing companies guide.

The 284,452 establishments are mostly private. Bebop finds private manufacturers from a plain-language description (process, material, size, region), explains why each fits and researches each account.

Worked example

Illustrative example. The company and figures are invented to show the method.

Ridgeback Metalworks (ridgeback.example) has 85 employees in Ohio. Revenue: 55% CNC machining of customers' parts on a job basis, 35% its own line of hydraulic hose fittings, 10% repairing customers' machine tools.

1. Primary NAICS code: 332710 Machine Shops, the largest revenue share.
2. Other codes to list: 332912 Fluid Power Valve and Hose Fitting Manufacturing for the product line, and 811310 for machinery repair.
3. Size: 85 employees, averaged over 24 months, is small under 332710 (500) and 332912 (1,000). Repair work under 811310 uses receipts instead: $12.5 million.
4. SIC for a bank form: 3599, the SIC code that maps to 332710.
5. Tax return: activity code 332000.

Next step: see how plants are organized to buy in the manufacturing companies guide.