A size standard is a specific number, not a feeling. The Small Business Administration sets a ceiling for every industry code, and whether you count as small for a given contract depends on where your numbers sit against that one ceiling, not against your own sense of how big you are.
What a size standard actually measures
Every NAICS code, the six-digit label the government uses for an industry, carries its own ceiling: either a dollar amount in average annual receipts or a headcount in employees. SBA sets and periodically updates these ceilings, and they vary a great deal. A code for a consulting service might cap out at a few million dollars in receipts, while a code for a manufacturer might allow several hundred employees. There is no single line that separates small from large across the whole economy. There is only the line for your code.
Small is relative to the code, not to you
The same business can be small under one NAICS code and large under another, because a solicitation gets judged against the primary code assigned to that specific procurement, not against every code your business could claim. A company that does both IT consulting and equipment resale might be comfortably small under one of those codes and over the ceiling under the other. Check the size standard for the code on the notice in front of you every time, rather than trusting a status you confirmed once and filed away.
How receipts and employees get counted
Most size standards run on receipts: a multi-year average of your gross revenue, so one unusually good year does not knock you out of small status by itself, and one unusually bad year does not make a large business small on paper. Manufacturing and a handful of other industries use employee counts instead, typically averaged over recent pay periods rather than a single headcount snapshot. Either way, the calculation looks backward across a stretch of time. It is not a snapshot of today.
Affiliation is the trap
The rule that catches people off guard is affiliation. SBA does not look only at your business, it looks at who controls it. A parent company, a controlling investor, or a business you depend on so heavily that the relationship functions like control, can have its size added to yours for the purpose of the ceiling. A business with twelve employees that is majority owned by a two-hundred-person company is not small under most standards, whatever its own headcount says. Common ownership, shared management, and identity-of-interest relationships (close family members running overlapping businesses, for instance) all get examined too. This is the part worth a second look if your business has outside investors, a parent entity, or one customer it could not survive losing.
Where to check
SBA publishes the full size standards table by NAICS code, and that table, not a rule of thumb from a colleague, is the authoritative source. Cross-reference two things before you bid: the size standard listed for the code, and the primary NAICS code printed on the specific notice, because that second number is what actually applies to that competition. The SBA size standards guide explains the table and how it is organized.
Quarry does not compute your size status for you. That number depends on receipts, ownership, and affiliations that only you can verify, and SBA has the final word if it is ever challenged. What is worth doing yourself, every time, is checking the standard against the actual code on the notice in front of you, not the one you remember from the last one.