Unit Converter

What Is a Unit Converter?

This free unit converter converts between units of length, weight, temperature, speed, area, volume, data, and energy — instantly with no button click needed. Whether you are cooking and need to convert cups to millilitres, travelling and need to convert miles to kilometres, shipping a package and need to convert pounds to kilograms, or studying physics and need to convert joules to kilowatt-hours — this unit converter handles all eight measurement categories in one place.

In fact, unit conversion is one of the most searched topics on the internet globally. The metric and imperial systems coexist in daily life — Australia, the UK, and most of the world use metric, while the US, Liberia, and Myanmar primarily use imperial. This unit converter bridges both systems instantly for every common measurement type.

How Are Units Converted?

Most unit conversions use a simple multiplication formula: Result = Input Value × Conversion Factor. All units in each category are stored relative to a base unit. To convert from Unit A to Unit B: first convert A to the base unit, then convert the base unit to B.

Temperature is the only conversion that uses addition and subtraction as well as multiplication — it cannot be handled by a simple conversion factor. All other categories use the base-unit multiplication method shown above.

How to Use This Unit Converter

• Select a category: Click any of the 8 category buttons — Length, Weight, Temperature, Speed, Area, Volume, Data, or Energy.
• Enter a value: Type your value in the From field. The result appears instantly in the To field — no button needed.
• Select units: Use the dropdowns below each field to select your source and target units. The result updates instantly when you change either dropdown.
• Swap direction: Click the ⇄ button to instantly reverse the conversion — swapping both the values and the units.
• Convert in reverse: You can also type in the To field to convert in the reverse direction.
• Quick reference: The quick reference table below the converter shows the most common conversions for the selected category at a glance.

What Your Result Means

The green result panel shows your conversion with 7 significant figures of precision — sufficient for all practical purposes including cooking, construction, science, and engineering. The result label below the main value shows the full conversion statement (e.g. “5 kilometres = 3.10686 miles”) for clarity. The quick reference table gives you the most commonly needed conversions for the active category so you can cross-check at a glance.

Is This Unit Converter Accurate?

Yes — this unit converter uses internationally accepted conversion factors from the NIST (National Institute of Standards and Technology) and SI (International System of Units) standards. The inch-to-centimetre conversion (2.54) is an exact defined value. The mile-to-kilometre conversion (1.609344) is the exact international standard. Temperature conversions use the exact formula definitions. All other conversions are based on official SI or international standard factors.

How to Choose Your Category

• Length: Metres, kilometres, centimetres, millimetres, miles, yards, feet, inches, nautical miles. Use for distance, height, dimensions.
• Weight: Kilograms, grams, milligrams, tonnes, pounds, ounces, stone. Use for body weight, cooking, shipping.
• Temperature: Celsius, Fahrenheit, Kelvin. Use for weather, cooking, science.
• Speed: m/s, km/h, mph, knots, ft/s. Use for driving, aviation, weather, sports.
• Area: Square metres, square kilometres, hectares, acres, square miles, square feet, square inches. Use for land, flooring, property.
• Volume: Litres, millilitres, cubic metres, US gallons, UK gallons, cups, fluid ounces, tablespoons, teaspoons. Use for cooking, fuel, liquids.
• Data: Bytes, kilobytes, megabytes, gigabytes, terabytes, bits, kibibytes, mebibytes. Use for file sizes, storage, internet speeds.
• Energy: Joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, BTU. Use for nutrition, electricity, physics.

Is This Unit Converter Suitable for Students?

Yes — this unit converter is an essential tool for science, physics, chemistry, and mathematics students. Unit conversion is a core skill tested in every science curriculum. The quick reference table and instant conversion help students check their manual calculations and develop an intuitive feel for the relative size of different units. The formula section in this page explains the conversion methodology so students understand how the conversion works, not just the answer.

Is This Unit Converter Suitable for Professionals?

Yes — engineers, architects, chefs, nurses, pharmacists, pilots, import/export professionals, and scientists all convert units daily. This unit converter covers the eight most common measurement categories needed in professional work. For specialised professional applications (medical dosing, chemical concentrations, engineering tolerances), always verify conversions against your professional standards — this unit converter is a general-purpose tool.

Can I Use This Unit Converter for Cooking?

Yes — the Volume and Weight categories cover all common cooking conversions. Convert cups to millilitres, tablespoons to teaspoons, ounces to grams, and pounds to kilograms instantly. The Temperature category covers oven temperature conversions between Celsius and Fahrenheit — essential when following recipes from different countries. Note that cooking conversions between weight and volume (e.g. cups of flour to grams) depend on the ingredient density — this unit converter handles volume-to-volume and weight-to-weight conversions only.

Common Mistakes When Converting Units

• Confusing US and UK gallons: The US gallon (3.785 litres) and the UK/Imperial gallon (4.546 litres) are different. This unit converter includes both — always select the correct one for your country.
• Confusing mass and weight: Technically, kilograms measure mass and Newtons measure weight (force). In everyday use, “weight” in kilograms refers to mass. This unit converter uses the everyday convention where kg and pounds are both in the Weight category.
• Calories vs kilocalories: Food “Calories” (with a capital C) are actually kilocalories (kcal). A 200-calorie chocolate bar contains 200 kcal = 200,000 small calories (cal). This unit converter includes both — use Kilocalorie for food energy.
• Binary vs decimal data units: 1 kilobyte (KB) = 1,000 bytes in the SI definition, but 1 kibibyte (KiB) = 1,024 bytes in the binary definition. Storage manufacturers use decimal (KB=1000), operating systems often use binary (KiB=1024). This unit converter includes both — select carefully.
• Temperature: forgetting to use the formula, not a factor: You cannot convert Celsius to Fahrenheit by multiplying by a single factor. The formula requires both multiplication and addition: F = (C × 1.8) + 32. This unit converter handles the formula automatically.

Limitations of This Unit Converter

This unit converter covers the eight most common measurement categories with the most frequently needed units in each. It does not cover all possible units — specialised units such as barrels (oil), fathoms (nautical depth), furlongs, chains, or highly specialised scientific units are not included. It converts between units of the same physical quantity only — it cannot convert weight to volume (which requires knowing the density of the substance). For highly specialised unit conversions, consult a dedicated reference for your field.

Unit Converter — Frequently Asked Questions