How many fluid ounces are there in one gallon?

One gallon is equivalent to 128 fluid ounces. This relationship is grounded in the United States customary system of measurement, where one gallon is defined as containing exactly this amount of fluid ounces. Understanding this conversion is crucial for fertilizer applicators as it allows them to accurately measure and mix fertilizers when applying them, ensuring effective and proper application rates. Using the correct volume measurements helps prevent over-application or under-application, which can affect crop yield and environmental quality.