SIC and NAICS Codes by Website
Most company records start with a domain and little else. This guide shows how to turn a website into an approximate SIC or NAICS industry code, where that works well, where it does not, and how to run it at scale.
What SIC codes are
The Standard Industrial Classification is the older US system for grouping businesses by their main activity. It was introduced in the 1930s and received its last full revision in 1987.
Each code narrows down from a broad division to a specific industry. The 1987 manual is organised in four levels, shown below with a restaurant as the example.
Division GRetail Trade, the broad division58Major group: Eating and Drinking Places581Industry group: Eating and Drinking Places5812Industry: Eating PlacesStructure in numbers
- 11 divisions, lettered A to K
- 83 two-digit major groups
- 416 three-digit industry groups
- About 1,004 four-digit industries
Why it ages badly
Because the list stopped changing in 1987, it has no clear home for software platforms, streaming, cloud hosting, online marketplaces or social networks. Those businesses get forced into broad service codes.
Where you still see it
SIC codes still appear in securities filings, in many purchased company lists, in older CRM records and in some insurance and compliance files. That is why enrichment projects often need both systems.
What NAICS codes are
The North American Industry Classification System was introduced in 1997 by the United States, Canada and Mexico to replace their national systems, including the US SIC. It is reviewed every five years, and the 2022 edition is the current one at the time of writing.
NAICS has 20 sectors and codes from two to six digits. The first five digits are shared by the three countries, and the sixth digit carries national detail.
72Sector: Accommodation and Food Services722Subsector: Food Services and Drinking Places7225Industry group: Restaurants and Other Eating Places72251NAICS industry, the deepest level shared across countries722511National industry: Full-Service RestaurantsSIC in short
- Up to 4 digits
- Frozen since 1987
- US only
- Strong on manufacturing detail
- Thin on internet and software businesses
NAICS in short
- 2 to 6 digits
- Reviewed every 5 years
- Shared by the US, Canada and Mexico
- Production oriented: grouped by how goods and services are made
- Better coverage of information and digital industries
Can you get an industry code from a website?
Yes, as an estimate. A website tells you what a business talks about and sells. An official code describes a legal entity and its main source of revenue, which the website does not always reveal.
Works well
- Single business companies with one clear offering
- Restaurants, clinics, law firms, dentists, hotels
- Software and online service providers
- Retailers whose product range is visible
- Schools, universities and public bodies
Needs care
- Conglomerates with many divisions on one domain
- Manufacturers that sell through distributors
- Holding companies and investment offices
- Companies whose site is mostly a careers page
- Agencies that describe their clients more than themselves
Do not code
- Parked and for-sale domains
- Personal blogs and hobby sites
- URL shorteners and hosting infrastructure
- Pure content sites with no business behind them
A categorized database helps with the third column too. Every domain carries a web filtering label, so parked domains, hosting infrastructure and personal sites can be removed before any code is assigned.
Mapping website categories to NAICS sectors and SIC groups
The table shows how common website categories line up with industry codes. It is a starting point for your own crosswalk, written at the sector and major group level where the match is most reliable.
| Website category (IAB v3 or filtering) | Likely NAICS sector | Likely SIC division or major group | Fit |
|---|---|---|---|
| Restaurants & Dining | 72 Accommodation and Food Services | 58 Eating and Drinking Places | High |
| Travel > Hotels and Motels | 72 Accommodation and Food Services | 70 Hotels and Other Lodging Places | High |
| Medical Health, Health & Medicine | 62 Health Care and Social Assistance | 80 Health Services | High |
| Education, Education/Reference | 61 Educational Services | 82 Educational Services | High |
| Real Estate | 53 Real Estate and Rental and Leasing | 65 Real Estate | High |
| Online Banking, Financial Services | 52 Finance and Insurance | 60 to 67, Finance, Insurance and Real Estate | Medium |
| Legal services, Government & Legal | 54 Professional, Scientific, and Technical Services, or 92 Public Administration | 81 Legal Services, or Division J | Medium |
| Computers & Technology, Software | 51 Information, or 54 Professional, Scientific, and Technical Services | 73 Business Services | Medium |
| CDN / Hosting / Infrastructure | 51 Information | 73 Business Services | Medium |
| News/Media | 51 Information | 27 Printing and Publishing, or 48 Communications | Medium |
| Automotive & Transportation | 44 to 45 Retail Trade, 48 to 49 Transportation, or 31 to 33 Manufacturing | 55 Automotive Dealers, Division E, or Division D | Low |
| Shopping | 44 to 45 Retail Trade | Division G Retail Trade | Low |
| Food & Drink | 72, 44 to 45, or 31 to 33 | 58, Division G, or 20 Food and Kindred Products | Low |
| Gambling | 71 Arts, Entertainment, and Recreation | 79 Amusement and Recreation Services | High |
| Sports & Recreation | 71 Arts, Entertainment, and Recreation, or 44 to 45 Retail | 79 Amusement and Recreation, or Division G | Medium |
| Religion & Spirituality | 81 Other Services (except Public Administration) | 86 Membership Organizations | High |
| Advertising/Marketing | 54 Professional, Scientific, and Technical Services | 73 Business Services | Medium |
| Job Search/Careers | 56 Administrative and Support Services, or 51 Information | 73 Business Services | Medium |
"Fit" describes how often the category alone points to the right sector. Low fit rows need a second signal, for example the deeper IAB tiers or the presence of a shop, before a code is assigned.
Why categories and industry codes disagree
The two systems answer different questions. Knowing the main reasons for disagreement lets you set rules instead of fixing records one at a time.
Content versus revenue
A recipe blog and a restaurant group are both about food. Only one of them earns money by serving meals, so they belong in different sectors.
Production versus audience
NAICS groups firms by how they produce. A website category groups pages by subject. A car maker, a car dealer and a car magazine share a subject but sit in three sectors.
Entity versus domain
One company can run many domains, and one domain can serve many legal entities. Codes belong to entities, so roll domains up to the company before you finalise a code.
Several labels per site
Our records carry several ranked categories per domain. The top category usually drives the code, while secondary labels flag diversified businesses.
Enrichment workflow: from domain list to coded accounts
This is the workflow most data teams use when they add industry codes to CRM accounts, lead lists or supplier files from a categorized website database.
- Normalise the domains. Strip protocols, paths and "www", lower-case everything and remove email provider domains such as free webmail. Keep one row per registrable domain.
- Join to the category file. Match each domain to its IAB v3 tiers and web filtering labels. Our data dictionary lists every column you can join on.
- Filter out non-businesses. Drop parked domains, personal blogs, hosting infrastructure and URL shorteners using the filtering labels. They should never receive an industry code.
- Apply your crosswalk. Map the deepest reliable IAB tier to a NAICS code at two, three or four digits, and to a SIC major group. Store the mapping version so you can rerun it later.
- Score confidence. Mark high, medium or low fit based on the crosswalk row and on whether the secondary labels agree. Low fit records go to review or stay at sector level only.
- Reconcile with existing codes. Where a record already has a code from a filing or a data vendor, keep it and use the website category as a check. Large disagreements often reveal outdated records.
- Refresh on a schedule. Companies pivot. A monthly refresh of the category file keeps codes in step with what the website actually says today.
How deep should a website based code go?
Depth is a trade-off between precision and how often you are right. Pick the depth per use case rather than one rule for every record.
| Depth | Example | Typical use | Guidance |
|---|---|---|---|
| NAICS 2 digits | 62 Health Care and Social Assistance | Market sizing, territory planning, dashboards | Safe for most records with a clear top category |
| NAICS 3 digits | 621 Ambulatory Health Care Services | Segmentation, campaign lists, routing | Good when the IAB Tier 2 label is specific |
| NAICS 4 digits | 6212 Offices of Dentists | Vertical sales plays, niche lists | Use when Tier 3 or Tier 4 labels agree |
| NAICS 6 digits | 621210 Offices of Dentists | Regulatory or contract work | Confirm with the entity record, not the website alone |
| SIC 2 digits | 80 Health Services | Legacy reports and older CRMs | Derive from the same crosswalk as NAICS |
| SIC 4 digits | 8021 Offices and Clinics of Dentists | Systems that require a full SIC field | Only for high fit categories |
Use cases for SIC and NAICS enrichment
Teams buy categorized domain data for industry coding because their records arrive with a website and nothing else. These are the most common projects.
Sales and lead generation
Score inbound sign-ups by sector, route them to the right team and build account lists by industry. See lead generation and sales intelligence.
Market research
Count businesses by sector and country from their web presence, then compare with official statistics coded in NAICS. See market research intelligence.
Risk and compliance
Flag merchants or suppliers whose website does not match the industry they declared. A pharmacy coded as a gift shop deserves a second look.
Data products
Data vendors add industry fields to firmographic files and keep them current with monthly category refreshes. Our company firmographic data guide covers the related fields.
Spend and supplier analytics
Procurement teams code vendor lists by industry to see where money goes. Website categories fill the gaps where suppliers never supplied a code.
B2B advertising
Build industry audiences for account based campaigns, then reach them with contextual placements on matching sites. See audience segmentation and targeting.
What you receive with the categorized database
The database ships as downloadable files that you join to your own records. Industry coding sits on top of the category fields below.
| Field group | What it holds | Role in industry coding |
|---|---|---|
| IAB v3 Tier 1 to Tier 4 | Up to four levels of the IAB Content Taxonomy | Main input for the crosswalk to NAICS and SIC |
| IAB v2 Tier 1 to Tier 4 | The previous taxonomy edition, for older systems | Keeps existing mappings working |
| Web filtering categories | One or more of 59 labels, ranked by relevance | Removes non-business sites and flags regulated sectors |
| Personas | Audience types a site attracts | Separates B2B from consumer focused businesses |
| Country | Country association of the domain | Chooses the right national code set |
| Popularity groups | Global and country level popularity bands | Prioritises review of the most visible accounts |
You can look up single domains with the domain category checker, read the full category list on the taxonomy page, or see sector level lists such as healthcare domains and legal services domains.
Quality checks before you trust a code
A short checklist keeps website based codes honest. Run it on a random sample of each batch before codes reach a production system.
Sample review
- Pick 100 random coded records per batch
- Open each site and confirm the sector
- Record agreement rate by fit level
Distribution check
- Compare sector shares with what you expect
- Watch for sudden jumps in one sector
- Investigate sectors that are near zero
Version control
- Store the crosswalk version on every record
- Keep the source category next to the code
- Rerun after taxonomy or NAICS edition updates
If you are also deciding how to label industries without codes, our guide to website to industry classification covers custom industry lists, and the website classification dataset page explains the training data side.
Records outside North America
NAICS and US SIC are North American systems. Global account files usually need a second code family, and the website category gives you a neutral bridge between them.
| System | Where it is used | How to handle it |
|---|---|---|
| ISIC | The United Nations international reference classification | Useful as a common layer when you report across many countries |
| NACE | Statistical classification of economic activities in the European Union | Map from the same website categories; check which revision your data partners use |
| UK SIC | United Kingdom company registrations and statistics, built on NACE | Not the same as US SIC despite the shared name, so never mix the two code lists |
| National variants | Many countries keep their own adaptation of ISIC or NACE | Use the country field in our file to choose the right target system |
Frequently asked questions
Can you get a NAICS code from a website?
You can get an approximate NAICS sector or subsector from what a company website is about. An official code depends on the legal entity and its main revenue source, so treat website based codes as an estimate for segmentation, routing and analytics.
Is SIC still used?
Yes. Federal statistics moved to NAICS from 1997, but SIC codes still appear in securities filings, older CRM records, credit and compliance files, and many purchased lists. Many teams keep both.
How many digits do SIC and NAICS codes have?
SIC codes have up to four digits. NAICS codes have two to six digits, where the first two give the sector and the sixth digit is national detail.
Why do website categories not map one to one to industry codes?
A website category describes content, while an industry code describes how a business earns its money. A recipe blog and a restaurant both talk about food but belong to different industries, so mappings need confidence levels and review.
Which code system should I use for enrichment?
Use NAICS when you compare with government statistics or public sector data, and keep SIC where downstream systems or older records still expect it. Store the website category next to both so you can remap later.
Do you deliver a ready made crosswalk?
Licence holders can discuss a crosswalk from our categories to NAICS sectors and SIC major groups for their use case. Tell us which code edition and depth your systems need when you contact us.
Add industry codes to every company domain
License the categorized domain database and build SIC and NAICS fields on top of IAB and web filtering categories, refreshed every month.
Talk to us See pricingIAB and the IAB Content Taxonomy are trademarks of the Interactive Advertising Bureau. They are used here only to identify the taxonomy discussed. URL Categorization Database is not affiliated with, sponsored or endorsed by the Interactive Advertising Bureau. SIC and NAICS are public classification systems maintained by government bodies.