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Unit Converter
Convert between units of length, weight, volume, and temperature. Supports metric, imperial, and US customary units with bidirectional conversion.
62.137119
Conversion⧉
100 Kilometers (km) = 62.137119 Miles
Quick Reference — Length
1 mile = 1.609 km1 inch = 2.54 cm1 foot = 30.48 cm1 yard = 0.914 m
Planning notes, formulas, and examples
About the Unit Converter
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 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 updates 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.
When This Page Helps
Memorizing conversion factors is impractical, especially for less intuitive pairs like fluid ounces to milliliters or stone to kilograms. This calculator keeps the common length, weight, volume, and temperature conversions on one screen and updates in both directions, which makes it easier to check the number you need without reworking the formula by hand.
How to Use the Inputs
- Select a conversion category: Length, Weight, Volume, or Temperature.
- Choose the "from" and "to" units.
- Enter a value — the converted result appears in the output panel.
- Swap units with one click to reverse the conversion.
- Common conversions are shown below for quick reference.
Formula used
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 + 273.15Example Calculation
Result: 62.14 miles
100 kilometers × (1 mile / 1.60934 km) = 62.14 miles. The conversion factor is approximately 0.6214 miles per kilometer.
Tips & Best Practices
- For a quick km↔mile estimate: multiply km by 0.6 or miles by 1.6.
- For Celsius↔Fahrenheit quick estimate: double °C and add 30 (roughly correct for everyday temperatures).
- Remember: a liter of water weighs approximately 1 kilogram (exactly 1 kg at 4°C).
- US customary and Imperial gallons are different! US gallon = 3.785 L, Imperial gallon = 4.546 L.
- When cooking, weight measurements (grams) are more accurate than volume measurements (cups) for dry ingredients.
A Brief History of Measurement Systems
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.
Common Conversion Mistakes to Avoid
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.
Temperature Scales Explained
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.
Sources & Methodology
Last updated:
Frequently Asked Questions
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.