NAICS vs SIC Codes: What Manufacturers Need to Know

NAICS vs SIC codes: NAICS and SIC are two systems of numeric industry codes. NAICS is the current six-digit standard used by U.S., Canadian and Mexican statistical agencies; SIC is the older four-digit system it replaced, still found in many lists and filings.

SIC: the older system

The Standard Industrial Classification (SIC) dates from the 1930s and was last revised in 1987. Codes have four digits; manufacturing is Division D, major groups 20 to 39 (for example 34 is fabricated metal products, 35 industrial machinery). SIC is still used for company filings at the SEC and by many list vendors and older databases.

NAICS: the current standard

The North American Industry Classification System (NAICS) replaced SIC in 1997 and is shared by the United States, Canada and Mexico. Codes have up to six digits, read from broad to narrow: the first two are the sector (manufacturing is 31 to 33), then subsector, industry group, industry and national industry. NAICS is reviewed every five years, most recently in 2022, which adds and splits industries as the economy changes.

The same shop, two codes

The systems do not map one to one: a single SIC code can split across several NAICS codes and the other way round, so a conversion table is a starting point, not an answer.

Using them to build a target list

• Codes are often self-reported or assigned by a data vendor, and a company may have several. Treat them as a filter, then check websites and capabilities.
• Search with both systems when a list mixes sources, and add keywords for the processes you sell into.
• Company pages on Factur data list both NAICS and SIC codes where the record has them.
• Not sure which code fits? The NAICS code lookup finds the 2022 NAICS code for a description, product or keyword, with the corresponding SIC code where one is on record.

The 2026 study groups quotes by the account’s primary industry label (Machinery, Plastics…), not by NAICS code; 48% of quoted opportunities have no industry. See which industries send the most RFQs.

In the data

• Which industries send the most RFQs
• NAICS code lookup: find your industry code
• U.S. company data by state (Insights)

Figures are from the Factur 2026 U.S. Manufacturing Sales Study, November 2025 – October 2026. From Factur’s outbound prospecting for U.S. manufacturing suppliers: every opportunity that reached a quote, its amount, and whether it became a purchase order, plus the calls and emails logged in the CRM, over the 12 months November 2025 – October 2026 compared with the 12 before, by opportunity close date.

More terms

• RFQ (request for quote)
• Quote-to-PO rate
• Purchase order (PO)
• Sales development vs business development
• Touches per quote
• All terms

Factur runs outbound prospecting for U.S. manufacturers · facturmfg.com · More free data on U.S. companies by state: Insights