Convert between units of length, weight, volume, and temperature. Supports metric, imperial, and US customary units with instant bidirectional conversion.
Need to convert kilometers to miles, kilograms to pounds, liters to gallons, or Fahrenheit to Celsius? This universal unit converter handles the four most common conversion categories — length, weight, volume, and temperature — with instant, bidirectional results.
Each category includes the most popular metric, imperial, and US customary units. Simply select a category, enter a value in either field, and the conversion happens automatically in both directions. No need to remember formulas or look up conversion factors.
Unit conversion is one of the most common everyday calculations, whether you are cooking with a recipe from another country, interpreting weather forecasts, understanding product specifications, or converting measurements for travel, science, or engineering.
This structured approach transforms vague productivity goals into measurable targets, making it easier to track improvement and stay motivated toward meaningful professional achievements. By calculating this metric accurately, professionals gain actionable insights that support smarter work habits, more realistic scheduling, and improved work-life balance over time.
Memorizing conversion factors is impractical and error-prone. A quick lookup tool saves time and prevents mistakes — especially for less intuitive conversions like fluid ounces to milliliters or stone to kilograms. This calculator keeps all common conversions in one place.
The bidirectional design is key: enter a value in either unit and the other updates instantly. No need to think about which direction you are converting.
Length: 1 mile = 1.60934 km, 1 inch = 2.54 cm, 1 foot = 0.3048 m, 1 yard = 0.9144 m Weight: 1 lb = 0.453592 kg, 1 oz = 28.3495 g, 1 stone = 6.35029 kg Volume: 1 gallon = 3.78541 L, 1 cup = 236.588 mL, 1 fl oz = 29.5735 mL Temperature: °F = °C × 9/5 + 32, °C = (°F − 32) × 5/9, K = °C + 273.15
Result: 62.14 miles
100 kilometers × (1 mile / 1.60934 km) = 62.14 miles. The conversion factor is approximately 0.6214 miles per kilometer.
The metric system was created during the French Revolution (1795) to replace the chaotic mix of local units across Europe. It was designed to be universal and base-10. The International System of Units (SI), adopted in 1960, formalized metric as the global standard. Today, only the US, Myanmar, and Liberia have not officially adopted metric as their primary system, though all three use it in science and trade.
The most dangerous conversion errors involve confusing similar-sounding units: US gallons vs Imperial gallons, short tons (2,000 lbs) vs metric tonnes (2,204.6 lbs) vs long tons (2,240 lbs), and nautical miles (1.852 km) vs statute miles (1.609 km). The 1999 Mars Climate Orbiter crash was caused by a metric/imperial conversion error between NASA teams, demonstrating that even experts make this mistake.
Three main temperature scales exist: Fahrenheit (water freezes at 32°, boils at 212°), Celsius (freezes at 0°, boils at 100°), and Kelvin (freezes at 273.15, boils at 373.15). Fahrenheit provides more resolution for weather temperatures (each degree is smaller), while Celsius is more intuitive for science. Kelvin is essential for physics and chemistry calculations.
Metric uses base-10 units (meters, grams, liters) used by most of the world. Imperial/US customary uses feet, pounds, and gallons, primarily in the US, UK (partially), and a few other countries. Metric is used in science and international trade worldwide.
The US adopted British Imperial units before the metric system was standardized and never fully converted, despite Congress authorizing metric in 1866. Conversion costs, inertia, and cultural attachment have prevented a complete switch, though US science and military use metric.
A US gallon is 3.785 liters (128 US fluid ounces). An Imperial gallon is 4.546 liters (160 Imperial fluid ounces). The Imperial gallon is about 20% larger. This difference also affects pints, quarts, and fluid ounces.
°C to °F: multiply by 9/5 and add 32. °F to °C: subtract 32 and multiply by 5/9. Key reference points: 0°C = 32°F (water freezes), 100°C = 212°F (water boils), 37°C = 98.6°F (body temperature).
Kelvin is the SI unit for temperature, starting at absolute zero (the coldest possible temperature, −273.15°C). Each Kelvin equals one degree Celsius. Kelvin is used in science because it has no negative values, simplifying thermodynamic calculations.
Miles↔km, pounds↔kg, Fahrenheit↔Celsius, cups↔mL, inches↔cm, and gallons↔liters. These cover travel, cooking, weather, health (weight), and everyday measurements.