The world uses two dominant systems of measurement: the metric system (officially called the International System of Units, or SI) and the imperial system (used primarily in the United States). The metric system is built on multiples of 10, making conversions between units straightforward — 1 kilometer is exactly 1,000 meters, and 1 kilogram is exactly 1,000 grams. The imperial system, by contrast, uses historically derived units with irregular conversion factors: 1 foot is 12 inches, 1 mile is 5,280 feet, and 1 gallon is 8 pints.
The United States, Myanmar, and Liberia are the only countries that have not officially adopted the metric system for everyday use. In practice, the US uses metric extensively in science, medicine, military applications, and international trade — while daily life (road signs, grocery shopping, body weight) still uses imperial units. This creates a constant need to convert between the two systems, which is exactly what this converter handles instantly.
Length is one of the most frequently converted measurements. The base metric unit is the meter (m), and the US still uses inches, feet, yards, and miles for most everyday purposes:
Weight (technically mass) is commonly converted between pounds and kilograms. The base metric unit is the gram (g), and 1 kilogram = 2.20462 pounds:
Temperature conversion is slightly more complex because the three main scales have different zero points, so you can't simply multiply by a constant:
Volume conversions matter most in cooking, chemistry, and fuel measurement. The US uses teaspoons, tablespoons, cups, pints, quarts, and gallons — while the rest of the world uses milliliters and liters. Key conversions:
Expert guides and educational resources to help you master the math.
The US officially adopted metric in 1975 but never mandated it for consumers. Here are all the conversions you'll actually use, the mental shortcuts to do them in your head, and where metric already appears in US daily life.
