What Are SMBs? SBA Definition, Size Standards, and NAICS Codes

An SMB is a small and medium-sized business, a shorthand used in industry reports, lending, and technology marketing to describe companies that are neither startups nor Fortune 500 giants. The term itself has no legal weight. The federal government draws only one line: small or not small. The Small Business Administration sets that line through detailed, industry-specific size standards, and there is no separate federal category or program for “medium-sized” businesses. When people call a company “medium-sized,” they usually mean a firm that feels bigger than a corner shop but still fits inside the SBA’s small business threshold for its industry.

That distinction matters because every legal and financial benefit tied to size flows through the SBA’s small business classification. Small businesses make up 99.9 percent of all U.S. businesses and employ roughly 45.9 percent of the private workforce, so the classification reaches a large share of the economy.¹

How Federal Law Defines a Small Business

The Small Business Act sets the foundation. Under 15 U.S.C. § 632, a small business concern is one that is independently owned and operated and not dominant in its field of operation.² That language does two things at once. It requires genuine independence from larger entities, and it keeps a company that controls its market from claiming small business status regardless of its headcount or revenue.

The statute also authorizes the SBA Administrator to write detailed size standards using employee counts, revenue, net worth, or other factors suited to each industry. Those detailed standards sit in 13 CFR Part 121, and they are what actually decides whether a specific company qualifies.³

How the SBA Measures Business Size

The SBA does not use a single snapshot. It uses rolling averages that smooth out good years and bad years, seasonal hiring, and temporary revenue spikes. The two main metrics are employee count and annual receipts, though some industries use something else entirely.

Employee Count

For industries measured by headcount, the SBA averages your total employees across all pay periods for the preceding 24 calendar months.⁴ Part-time and temporary workers count the same as full-time staff. If the business has been operating for less than 24 months, the SBA averages whatever pay periods exist. The approach stops a company from timing a headcount cut right before applying for a contract.

Annual Receipts

For industries measured by revenue, the SBA typically averages total receipts over the most recently completed five fiscal years. For certain SBA loan and bond programs, a business operating at least three years can elect either a three-year or five-year average. Receipts include all revenue from any source before subtracting expenses, though the regulation carves out specific items like net capital gains and taxes collected for a taxing authority.⁵

Alternative Metrics

A few industries use measures that have nothing to do with headcount or revenue. Commercial banks and credit unions, for example, are measured by total assets, with the current threshold set at $850 million. That figure is calculated by averaging the assets reported on the institution’s four quarterly financial statements for the preceding year. Electric power generation and distribution firms used to be measured by megawatt hours of output, but the SBA replaced that metric with a 500-employee standard in 2014.³

NAICS Codes and Why Your Industry Sets Your Threshold

The SBA does not use one universal cutoff. It ties each size standard to a North American Industry Classification System code. NAICS organizes every kind of economic activity into sectors, and each sector has its own threshold. The differences can be dramatic. An iron and steel manufacturer qualifies as small with up to 1,500 employees. A grocery retailer hits the ceiling at $40 million in average annual receipts.³

Finding your NAICS code is the first step in checking whether you qualify. The U.S. Census Bureau maintains a searchable database where you can look up codes by keyword or browse the full classification manual.⁶ For federal contracting, the contracting officer assigns the NAICS code in the solicitation, and you must meet the size standard for that specific code, not necessarily the one your business normally uses.

The Affiliation Rule Most Owners Miss

This is where most qualification problems actually come from. Even if your individual company falls below the size threshold, the SBA will combine your employees or revenue with those of any affiliated businesses. Affiliation exists whenever one entity controls or has the power to control another, or when a third party controls both. The power to control does not have to be exercised. It just has to exist.⁷

The SBA looks at several factors:

Owning 50 percent or more of voting stock creates a presumption of control. Even a minority stake can trigger affiliation if your block is the largest compared to other holders.
If the same officers or directors control the boards of two companies, those companies are affiliated.
Family members, spouses, or business partners who own separate companies may be treated as one party. Businesses owned by close relatives are presumed affiliated if they share resources, subcontract to each other, or exchange loans.
If 70 percent or more of your receipts over the past three fiscal years came from a single other company, the SBA may presume affiliation on economic-dependence grounds.

The SBA weighs the totality of the circumstances. No single factor has to be decisive on its own.

Why the Small Business Label Matters

The federal government has a statutory goal of awarding at least 23 percent of prime contracting dollars to small businesses.⁸ That target drives billions of dollars in set-aside contracts each year. Only companies that meet the SBA’s size standard for the relevant NAICS code can compete for those set-asides, so losing small business status closes off an entire market.

Classification also opens the door to SBA lending. The 7(a) program, the SBA’s most common financing tool, requires borrowers to meet SBA size requirements, operate for profit, and be located in the United States.⁹ Those loans can fund working capital, real estate, equipment, and business acquisitions. Small businesses employ approximately 62.3 million Americans, close to half the private-sector workforce, and the SBA’s programs are built around that footprint.¹

Size Standards Change, So Check Before You Rely on One

Standards are not permanent. The SBA reviews them every five years and adjusts monetary-based thresholds for inflation at least that often.¹⁰ The most recent inflation adjustment was finalized in 2023, based on a rule published in late 2022.¹¹ A business that was too large under the old number might qualify under the new one, and the reverse also happens. If you sit near the boundary for your NAICS code, checking the SBA’s current table of size standards before each contract bid or loan application is worth the few minutes it takes.

1
U.S. Small Business Administration. United States 2025 Small Business Profile
2
Office of the Law Revision Counsel. 15 USC 632 – Definitions
3
eCFR. 13 CFR Part 121 – Small Business Size Regulations
4
eCFR. 13 CFR 121.106 – How Does SBA Calculate Number of Employees
5
eCFR. 13 CFR 121.104 – How Does SBA Calculate Annual Receipts
6
U.S. Census Bureau. North American Industry Classification System – NAICS
7
eCFR. 13 CFR 121.103 – How Does SBA Determine Affiliation
8
Congress.gov. Federal Small Business Contracting Goals
9
U.S. Small Business Administration. Terms, Conditions, and Eligibility
10
U.S. Small Business Administration. Size Standards
11
Federal Register. Small Business Size Standards: Monetary-Based Industry Size Standards