Someone asked me on Twitter, what determines a small farm? As I collected information for him, I realized that there are many definitions of a "small farm," and the answer you get depends on who you ask.
For example, the USDA's Economic Research Service, or ERS, has this to say in their definition of small farms:
In the past, ERS frequently used $50,000 in agricultural sales as the delineation between large and small farms. "Noncommercial" or small farms had sales less than $50,000, while "commercial" or large farms had sales of $50,000 or more.
To some extent, the cutoff between small and large farms is arbitrary, and cutoffs other than $50,000 are also used. The National Commission on Small Farms, for example, used a much higher cutoff in its definition of small farms: farms with sales less than $250,000. The Commission wanted to include more farm families of relatively modest means who may need to improve their net farm incomes. ERS has created a farm typology, with eight groups, that incorporates the Commission's $250,000 cutoff.
Their farm typology classification system is also helpful to take a look at. The upshot is, if you want to get a USDA grant, you'll want to find out whether you can be classified as a small farm according to their rules. State definitions vary, too. For example, the Washington State Department of Agriculture simply says, "WSDA defines a small farm as one where the farmer or farm family participates in the day-to-day labor and management of the farm, and owns or leases its productive assets."
But $50,000 or $250,000 is the top end. What about at the low end? For USDA purposes, you are a farm once you have $1,000 in agricultural sales in one calendar year.