Unit Converter

How Does the Formula Work?

This unit converter handles the five most common measurement categories: length, area, volume, weight, and temperature. Type a number in either field and the conversion happens instantly — no need to click a button.

All conversions use internationally standardized factors. Length, area, volume, and weight conversions multiply through a base unit (meter, square meter, cubic meter, kilogram). Temperature uses direct formulas since it is not a ratio-based scale.

Metric vs Imperial

The metric system (SI) is used by most countries worldwide. The United States, Liberia, and Myanmar are the only countries that have not officially adopted SI. In practice, the US uses a mix: miles and pounds in daily life, but meters and kilograms in science and medicine.

Key relationships: 1 inch = 2.54 cm (exact), 1 foot = 30.48 cm, 1 mile = 1.609 km, 1 pound = 0.4536 kg, 1 gallon (US) = 3.785 liters, 1 acre = 4,047 m².

Common Conversion Scenarios

Construction: feet/inches to meters for international plans. Cooking: US cups to milliliters. Travel: miles to kilometers, Fahrenheit to Celsius. Shipping: pounds to kilograms, cubic feet to cubic meters. Real estate: square feet to square meters, acres to hectares.

Precision and Rounding

This converter displays up to 6 decimal places for small values and uses scientific notation for extremely large or small numbers. For everyday use, 2 decimal places is usually sufficient. For engineering and scientific applications, verify the precision required by your project specifications.

Note that some conversion factors are exact by definition (1 inch = 2.54 cm, 1 pound = 0.45359237 kg) while others are rounded approximations. The factors used in this converter are accurate to at least 6 significant digits, which exceeds the precision needed for virtually all practical applications.

Temperature Reference Points

Water freezes at 0°C = 32°F = 273.15 K. Water boils at 100°C = 212°F. Human body temperature is approximately 37°C = 98.6°F. Room temperature is roughly 20–22°C = 68–72°F. These landmarks help verify your conversions are reasonable. If a temperature conversion gives you a result that seems far from these reference points for everyday situations, double-check that you selected the correct units. A common mistake is accidentally converting Kelvin when you meant Fahrenheit.

The Metric and Imperial Systems

The world uses two primary measurement systems. The metric system (SI), used by over 95 percent of the world's population, is based on powers of ten — meters, liters, grams, and Celsius. The imperial system, used primarily in the United States, Myanmar, and Liberia, uses feet, gallons, pounds, and Fahrenheit. The US customary system differs slightly from British imperial — a US gallon is 3.785 liters while a British imperial gallon is 4.546 liters. This converter handles both systems with instant bidirectional conversion across five categories: length, area, volume, weight, and temperature.

Length Conversion Essentials

Length is the most commonly converted unit. Key conversions: 1 inch equals 2.54 centimeters exactly (defined since 1959). 1 foot equals 30.48 centimeters. 1 yard equals 0.9144 meters. 1 mile equals 1.609344 kilometers. In everyday life, knowing that 1 meter is about 3.28 feet and 1 kilometer is about 0.62 miles covers most situations. Construction and manufacturing frequently require converting between metric and imperial — international blueprints may use meters while US suppliers sell lumber in feet and inches.

Area and Volume

Area conversions square the linear conversion factor. Since 1 foot equals 0.3048 meters, 1 square foot equals 0.0929 square meters. One acre (43,560 square feet) equals 0.4047 hectares. Real estate in the US uses square feet while most countries use square meters. Volume conversions are cubed: 1 cubic foot equals 0.0283 cubic meters. The most confusing volume conversions involve gallons: 1 US gallon equals 3.785 liters, while 1 imperial gallon equals 4.546 liters. Cooking conversions between cups, tablespoons, and milliliters are essential when following international recipes.

Weight and Mass

Weight conversions: 1 pound equals 0.4536 kilograms. 1 ounce equals 28.35 grams. 1 stone (14 pounds) equals 6.35 kilograms — commonly used in the UK for body weight. 1 metric ton equals 1000 kilograms or 2204.6 pounds. Grocery shopping internationally requires knowing that 500 grams is roughly 1.1 pounds. Gold is measured in troy ounces (31.1 grams) while regular ounces are avoirdupois (28.35 grams). Medical dosages worldwide use the metric system exclusively regardless of the country.

Temperature

Temperature conversion between Celsius and Fahrenheit is uniquely nonlinear. The formula is F equals C times 9 divided by 5 plus 32. Key reference points: water freezes at 0 degrees Celsius and 32 degrees Fahrenheit; water boils at 100 Celsius and 212 Fahrenheit; normal body temperature is 37 Celsius and 98.6 Fahrenheit; room temperature is about 20 to 22 Celsius and 68 to 72 Fahrenheit. The crossover point where both scales read the same is minus 40 degrees. For a dedicated temperature tool with Kelvin and Rankine support use our Temperature Converter.

When You Need Conversions

Common scenarios requiring unit conversion include international travel, online shopping from foreign retailers, following recipes from different countries, scientific research, engineering projects with international specifications, importing building materials, calculating shipping weights, and comparing real estate listings across borders. This tool provides instant conversion with high precision making it useful for both quick estimates and exact calculations. All conversions use internationally recognized conversion factors defined by the National Institute of Standards and Technology (NIST) and the International Bureau of Weights and Measures (BIPM).