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NAICS & SIC Classification Reference · Since 1998
Find the right NAICS or SIC code
Official definitions, verified company data, and industry classification tools trusted since 1998.
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Top result for “plumbing contractor”
NAICS Match
238220
Plumbing, Heating, and Air-Conditioning Contractors
SIC Match
1711
Plumbing, Heating and Air-Conditioning
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Built on 28 years of industry classification experience and millions of U.S. company records used for code lookup, company targeting, data appending, and industry research.
What do you need help with?
You don’t need to understand NAICS or SIC codes first. Choose what you’re trying to do, and we’ll guide you.
Find the right code for my business
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Append NAICS and SIC codes to customer, supplier, vendor, or CRM records.
What are NAICS and SIC codes?
NAICS codes are six-digit industry codes used in the current North American Industry Classification System. They are commonly used for government statistics, business registration, contracting, lending, and market research.
SIC codes are four-digit industry codes from the older Standard Industrial Classification system. SIC is a legacy system, but it is still widely used in business databases, insurance, finance, public company records, and historical datasets.
Many users need both systems: NAICS for current classification needs and SIC for legacy business data, crosswalks, segmentation, and company research.
Where NAICS and SIC codes are used
Industry codes show up on real forms, applications, procurement systems, and business-data workflows.
Government contracting
SAM.gov registrations and many public-sector opportunities use NAICS codes to identify eligible vendors, applicable size standards, and the type of work being performed.
Look up codesBusiness loans
A mismatched industry code can affect how lenders compare your business, review eligibility, and evaluate risk against similar companies in your industry.
Choose the right codeTaxes and filings
Tax forms and business filings often ask for a principal business activity. The right industry code helps describe what the business actually does.
Search NAICS codesRisk and vendor onboarding
Insurers, procurement teams, and vendor portals use industry classification to understand business activity, supplier categories, and operational risk.
Classify suppliersMarket research and prospecting
Industry codes turn a broad market into a countable group of companies, making it easier to size opportunities, segment accounts, and find better-fit prospects.
Find target companiesNAICS & SIC codes, explained
Plain-English answers to common questions about industry classification.
What is a NAICS code?
A NAICS code is a six-digit industry classification code from the North American Industry Classification System. It identifies what a business does and organizes companies by type of economic activity.
What is a SIC code?
A SIC code is a four-digit industry classification code from the Standard Industrial Classification system. SIC codes remain widely used in business data, financial records, insurance, marketing, and legacy datasets.
What is the difference between NAICS and SIC codes?
NAICS is the newer six-digit classification system used by U.S. federal statistical agencies. SIC is the older four-digit system that remains common in private-sector business data. Many users rely on both systems and use a SIC to NAICS crosswalk to compare them.
How do I find my business’s NAICS code?
Start with the business’s primary activity: what it mainly does, sells, produces, or provides. Search that activity, compare definitions, examples, and exclusions, and choose the code that best matches the business’s main activity.
Can a business have more than one NAICS or SIC code?
Yes. A business usually has one primary code for its main activity, but it may also use additional codes for secondary lines of business, different locations, government registrations, procurement portals, or internal data workflows.
Who assigns NAICS and SIC codes?
There is no single universal registry that assigns one code to every business for all uses. Businesses, agencies, lenders, data providers, procurement systems, and researchers may classify a company differently depending on their purpose and data source. For 28 years, SICCODE.com has helped businesses, researchers, and data teams interpret industry codes, compare classification systems, and identify the codes that best fit a company’s primary business activity.
How often do NAICS and SIC codes change?
NAICS is reviewed every five years. SIC is an older system that has not been revised in the same way, but it remains widely used in business databases and historical records.