If you’ve ever built a B2B target list, you’ve encountered SIC and NAICS codes — the two classification systems that sort businesses by industry. Choosing between them, or knowing when to use both, directly affects how precisely you can target. This article explains what each system is, how they differ, and which to use for B2B audience targeting.
What SIC and NAICS codes are
Both are standardized systems for classifying businesses by their primary economic activity, used heavily in B2B data targeting to filter companies by industry.
SIC (Standard Industrial Classification) is the older system, established by the US government in 1937. It uses four-digit codes to categorize businesses — for example, 7372 is “Prepackaged Software.” SIC was the dominant classification for decades and remains widely embedded in business databases, credit reporting, and marketing data despite being officially superseded.
NAICS (North American Industry Classification System) replaced SIC for official US government purposes in 1997. Developed jointly by the US, Canada, and Mexico, it uses six-digit codes and reflects a more modern economy — including industries that didn’t exist when SIC was designed, like web search portals and data processing. NAICS code 511210 is “Software Publishers.”
The practical reality in 2026: both systems coexist in B2B data. Government statistics and newer databases favor NAICS; many legacy business databases, credit files, and marketing lists still carry SIC codes. Good B2B data providers maintain both, letting you target by whichever fits your campaign.
Common questions
Which is better for B2B targeting, SIC or NAICS?
NAICS is generally better for modern, precise targeting because it has more granular categories and better reflects today’s economy — especially in technology, services, and digital industries that SIC handles poorly. However, SIC remains useful for broad targeting and for reaching legacy databases where SIC coverage is more complete. The best approach is using a data provider that supports both, then choosing per campaign based on which gives cleaner coverage for your target industries.
Why do both systems still exist if NAICS replaced SIC?
Inertia and embedded infrastructure. SIC codes are baked into decades of business records, credit files, regulatory filings, and marketing databases. Replacing them everywhere would be enormously expensive, so many systems simply kept SIC while adding NAICS alongside it. For data buyers, this means most quality B2B databases carry both codes per record, and you can target with either.
How many digits should I target on?
It depends on how precise you need to be. NAICS codes range from 2-digit (broad sector) to 6-digit (specific industry). Targeting on 2 or 3 digits gives you a wide net (e.g., “Manufacturing”); targeting on 6 digits gives you precision (“Breakfast Cereal Manufacturing”). Most B2B campaigns target at the 4- to 6-digit NAICS level or 4-digit SIC level — specific enough to be relevant, broad enough to reach meaningful volume.
Can a single company have multiple codes?
Yes. A company with diverse operations often carries a primary code plus secondary codes reflecting its other activities. A firm that both manufactures and distributes products might have manufacturing as its primary NAICS and wholesale distribution as a secondary. When targeting, decide whether you want companies where your target industry is their
primary activity or any company that touches that industry at all — the difference significantly affects list size.
What if my target industry doesn’t map cleanly to a code?
This is common for emerging or cross-cutting industries. When no single code captures your target, combine multiple codes (target several related NAICS codes together) or layer industry codes with other variables (company size, keywords in company name, technographic signals). A good data provider helps translate “companies like these” into the right combination of codes and filters rather than forcing your target into one imperfect code.
Do SIC and NAICS codes map to each other?
Partially. The US Census Bureau publishes concordance tables that map SIC codes to NAICS codes and vice versa, but the mapping is imperfect — some SIC categories split into multiple NAICS codes, and some NAICS categories didn’t exist in SIC at all. When precision matters, target on the native system your data is strongest in rather than relying on a converted mapping that may lose accuracy.
Which code system do data providers prefer?
Most quality B2B data providers maintain both and let the buyer choose. Providers built on government data lean NAICS; those built on legacy commercial databases often have richer SIC coverage. The provider’s coverage depth in your specific target industries matters more than which system they “prefer” — ask for record counts under both systems for your target before committing.
How this applies to your business
The practical workflow is to define your target industries in plain language first (“mid-size manufacturers,” “regional accounting firms”), then translate that into codes with your data provider’s help. Don’t start from the code system — start from who you’re trying to reach, then find the codes that capture them.
For most B2B campaigns, NAICS at the 4- to 6-digit level gives the best balance of precision and coverage in 2026. Use SIC as a complement when your data provider has stronger SIC coverage for a specific legacy industry, or when targeting databases that predate widespread NAICS adoption.
The biggest practical mistake is targeting too broadly — selecting a 2-digit sector code and reaching tens of thousands of irrelevant companies — or too narrowly, picking one hyper-specific 6-digit code and missing adjacent companies that are equally good prospects. Test your code selection against record counts before committing, and layer codes with firmographic filters (size, revenue, geography) to sharpen the target.
Iscope Digital’s
B2B Email & Postal Data service supports targeting by both SIC and NAICS across the
Bizline Direct database, with a count-and-quote process that shows you exact reach before you buy. For the broader picture of what’s in a B2B record, see
What is a full-record B2B contact vs an enriched record vs a basic record? 
