About 120 drops of water will fill a what? Teaspoon, tablespoon, or one-ounce shot glass?

While it might seem like a vague unit, the "drop" has a standardized basis in medicine and pharmacology. The metric measurement, called a *gutta*, is typically defined as 1/20th of a milliliter (mL). A standard US teaspoon holds almost exactly 5 mL of fluid. A quick calculation (20 drops/mL x 5 mL) shows that a teaspoon would contain about 100 drops. The 120-drop figure is a common real-world approximation that accounts for the fact that drops from a simple faucet or eyedropper are often slightly smaller than the official *gutta*.

In comparison, the other containers are far too large. A tablespoon is a much bigger unit, holding about 15 mL, or three times the volume of a teaspoon. It would take approximately 300 drops to fill. A one-ounce shot glass is even larger, with a capacity of nearly 30 mL. Filling that would require around 600 drops of water, making the tiny teaspoon the only logical fit.

The very formation of a drop is a small marvel of physics, governed by surface tension. This force causes water molecules to cohere, or stick together, pulling the liquid into the shape with the least possible surface area: a sphere. This tension is what allows water to hang from a tap before gravity finally pulls it down. The exact size of the resulting drop can be influenced by water temperature, purity, and the shape of the dropper's tip, which is why any measurement in drops is always an estimate.