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📏 Unit Converter

Convert between common units of length, weight, temperature, area and speed.

What is a Unit Converter?

A unit converter is a tool that converts a measurement from one unit to another within the same physical quantity — for example, converting 5 kilometres to miles, 100°F to Celsius, or 10 kilograms to pounds. Measurement unit systems vary by country and industry: most of the world uses the International System of Units (SI), while the United States, Liberia, and Myanmar still primarily use the imperial (US customary) system. Scientists worldwide use SI units regardless of their country's everyday system.

Unit conversion is needed constantly in everyday life and professional work: a chef following a foreign recipe needs to convert grams to ounces; a cyclist tracking speed in km/h needs miles per hour for an American app; a designer working with international clients converts centimetres to inches. Our converter supports five categories — Length, Weight, Temperature, Area, and Speed — covering the most commonly needed conversions with full precision, all running locally in your browser with no server calls.

How to Use the Unit Converter

  1. Select a Category — Length, Weight, Temperature, Area, or Speed — using the tab buttons.
  2. Enter the Value you want to convert in the number field.
  3. Choose the From unit (the unit you are converting from).
  4. Choose the To unit (the unit you want the result in).
  5. Click Convert — the result appears instantly with the full conversion label.

Why Use Our Unit Converter?

  • 100% Free — Convert unlimited values across all categories at no cost.
  • No Registration — No account or sign-up required.
  • Browser-Based — All conversions run client-side; your inputs are never sent to a server.
  • Five Categories — Length, Weight, Temperature, Area, and Speed covered in one tool.
  • High Precision — Results shown to up to 8 significant decimal places for scientific accuracy.

Frequently Asked Questions

Temperature uses different formulas than simple multiplication ratios. To convert Fahrenheit to Celsius: subtract 32, then multiply by 5/9. To convert Celsius to Fahrenheit: multiply by 9/5, then add 32. Kelvin is the absolute temperature scale used in science — Kelvin = Celsius + 273.15. Water freezes at 0°C / 32°F / 273.15K and boils at 100°C / 212°F / 373.15K.

One mile equals exactly 1.609344 kilometres, or approximately 1.61 km. Conversely, one kilometre equals approximately 0.6214 miles. A quick mental approximation: multiply kilometres by 0.6 to get a rough mile figure, or multiply miles by 1.6 for kilometres. For a marathon (26.2 miles), that's approximately 42.2 kilometres.

In everyday language, "weight" is used to mean mass. Technically, mass is the amount of matter in an object (measured in kilograms) and remains constant everywhere, while weight is the force of gravity on that mass (measured in Newtons) and changes depending on where you are. On the Moon, your mass is the same but you weigh about 1/6th as much. This tool converts units of mass: kilograms, pounds, grams, ounces, and more.

A knot is a unit of speed equal to one nautical mile per hour — approximately 1.852 km/h or 1.151 mph. Knots are the standard speed unit in aviation and maritime navigation worldwide because nautical miles are based on the Earth's geometry (one minute of arc of latitude), making navigation calculations more convenient. Aircraft airspeed and wind speed in weather forecasts are often given in knots.

Quick Facts

  • ✓ 100% free, no hidden fees
  • ✓ No account or login needed
  • ✓ Works in any browser
  • ✓ Your data never leaves your device
  • ✓ 5 categories: Length, Weight, Temperature, Area, Speed

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