Teaspoon (Metric)
The metric teaspoon equals 5 milliliters, standardized to simplify cooking and medical measurements in countries that use the metric system. Unlike the US teaspoon, the metric teaspoon is slightly larger (5 mL vs ~4.92892 mL) and is widely used in recipes, pharmaceutical dosing, and nutrition labeling. Its simplicity ensures consistency across recipes and instructions internationally.
Gallon (US)
The US gallon, symbol gal, equals 4 quarts, 8 pints, or 128 fluid ounces (~3.785 liters). Its origins trace to English wine and ale measures but were standardized in the US in the 19th century. Gallons are used for beverages, fuel, and large-volume recipes. While metric liters are the dominant unit of measurement in most countries, gallons remain widely used in the United States for everyday and industrial liquid measurements.