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.
Liter (L)
The liter (L) is a metric unit of volume, representing 1,000 milliliters. It originated in France as part of the metric system reforms of 1795, initially defined as the volume occupied by one kilogram of water at its densest point. Over time, the liter became a fundamental unit for measuring liquids in science, industry, and everyday life. Its decimal structure makes calculations and conversions straightforward, contributing to its widespread adoption around the world, even as some regions continue to use imperial measures in certain contexts.