Understanding SIC Codes: A Complete Guide
Learn how Standard Industrial Classification (SIC) codes work and how to use them for business research and industry analysis.
What Are SIC Codes?
Standard Industrial Classification (SIC) codes are four-digit numerical codes assigned by the US government to business establishments to identify the primary type of activity they are engaged in. The system was established in 1937 and remains widely used for:
- Classifying businesses by industry
- Economic analysis and research
- Government statistics and reporting
- Marketing and sales targeting
- Competitive analysis
SIC Code Structure
SIC codes follow a hierarchical structure with increasing specificity:
| Level | Digits | Example | Description |
|---|---|---|---|
| Division | Letter (A-K) | D | Manufacturing |
| Major Group | 2 digits | 35 | Industrial Machinery |
| Industry Group | 3 digits | 357 | Computer Equipment |
| Industry | 4 digits | 3571 | Electronic Computers |
The more digits, the more specific the classification. Two-digit codes represent broad industry groups, while four-digit codes identify specific industries.
Top Industries in Our Database
Our database of 87.6 million businesses covers all SIC code categories. Here are the largest industry groups:
| Industry | Businesses |
|---|---|
| Educational Services | 8,544,055 |
| Business Services | 6,846,647 |
| Engineering, Accounting, Research, Management, And Related Services | 5,840,187 |
| Health Services | 5,653,471 |
| Nonclassifiable Establishments | 5,463,377 |
| Real Estate | 3,335,208 |
| Wholesale Trade-durable Goods | 3,241,199 |
| Miscellaneous Retail | 2,584,177 |
| Home Furniture, Furnishings, And Equipment Stores | 2,429,598 |
| Social Services | 2,334,173 |
| Membership Organizations | 2,297,242 |
| Insurance Agents, Brokers, And Service | 2,280,867 |
| Depository Institutions | 2,172,651 |
| Legal Services | 2,112,335 |
| Security And Commodity Brokers, Dealers, Exchanges, And Services | 1,909,278 |
| Eating And Drinking Places | 1,697,937 |
| Communications | 1,680,823 |
| Executive, Legislative, And General Government, Except Finance | 1,508,879 |
| Construction Special Trade Contractors | 1,311,045 |
| Wholesale Trade-non-durable Goods | 1,298,395 |
How to Use SIC Codes for Business Research
- Identify your target industry — find the SIC code that best matches the businesses you want to reach
- Browse by industry — use our industry directory to see businesses broken down by state
- Filter business searches — use SIC codes in our business search to find specific companies
- Analyze competition — see how many businesses operate in the same SIC code in your area
- Evaluate market size — use employee and revenue data alongside SIC codes for market sizing
SIC vs NAICS Codes
While SIC codes remain widely used, the North American Industry Classification System (NAICS) was introduced in 1997 as a replacement. Key differences:
| Feature | SIC | NAICS |
|---|---|---|
| Digits | 4 | 6 |
| Categories | ~1,000 | ~1,000+ |
| Coverage | US only | US, Canada, Mexico |
| Updated | Last 1987 | Every 5 years |
| Usage | Still widely used | Federal standard |
Many business databases, including ours, continue to use SIC codes because they are well-established and widely understood.
Key Numbers
| SIC Industries | 1,004 |
| Major Groups | 84 |
| Industry Groups | 417 |
| Our Businesses | 87.6M |