Unit Converter Online — Convert Any Measurement Free
A unit converter online handles conversions across dozens of measurement categories — length, weight, temperature, volume, speed, area, pressure, energy, data storage, and more. Instead of remembering conversion factors or searching for a single-purpose calculator, one tool covers all the conversions you encounter across science, cooking, travel, and engineering.
Measurement Categories Covered
| Category | Example Units | Common Use Case |
|---|---|---|
| Length | m, ft, in, km, miles, cm | Height, distance, construction measurements |
| Weight / Mass | kg, lb, stone, g, oz, tonnes | Body weight, food portions, shipping |
| Temperature | °C, °F, K | Weather, cooking, scientific data |
| Volume | L, mL, fl oz, cups, gallons, pints | Cooking, fuel, liquid products |
| Speed | km/h, mph, m/s, knots | Vehicle speed, wind speed, running pace |
| Area | m², ft², acres, hectares | Land area, floor space, screen resolution |
| Data storage | bytes, KB, MB, GB, TB | File sizes, storage capacity, transfer speeds |
| Pressure | Pa, bar, psi, atm, mmHg | Tyre pressure, atmospheric pressure, medical |
| Energy | J, kJ, kcal, kWh, BTU | Nutrition labels, electricity, heating |
How to Use the Unit Converter
- Select the category. Choose the type of measurement you want to convert — length, weight, temperature, volume, and so on.
- Enter the value. Type the number you want to convert.
- Choose the source unit. Select the unit you are converting from.
- Read the results. All equivalent values in the available units for that category are shown instantly.
Why Unit Conversions Trip People Up
Mixed systems in everyday life
Most countries use metric for official purposes but encounter imperial measurements constantly — from US product labels and recipes, British body weight in stone, aviation altitudes in feet, and screen sizes in inches. Navigating between systems without a converter requires memorising dozens of arbitrary conversion factors.
Data storage prefixes are ambiguous
Kilobyte, megabyte, and gigabyte can mean different things depending on context. In computing, a kilobyte is traditionally 1,024 bytes (2¹⁰), but the SI definition is 1,000 bytes. The IEC introduced kibibyte (KiB), mebibyte (MiB), and gibibyte (GiB) to resolve the ambiguity — but the confusion persists. Hard drive manufacturers use the SI (1,000-byte) definition, which is why a 1 TB drive shows as ~931 GiB in an operating system using the binary definition.
Volume in cooking crosses systems frequently
US recipes use cups, tablespoons, and teaspoons; UK recipes use millilitres and grams; Australian tablespoons differ from US tablespoons (20 mL vs 15 mL). A volume converter is indispensable when cooking from international recipes.
Specialised Converters on This Site
For categories used most frequently, dedicated converters provide more detail and reference information:
- Temperature converter — Celsius, Fahrenheit, Kelvin with formula reference
- Weight converter — kg, lb, stone, grams, ounces with reference table
- Length converter — meters, feet, inches, miles, km with reference points
- Time converter — seconds, minutes, hours, days, weeks, months, years
Common Questions
How do I convert speed from km/h to mph?
Multiply km/h by 0.621371 to get mph. A quick approximation: divide by 1.6. So 100 km/h ≈ 62 mph (actual: 62.14 mph). The UK uses mph; most other countries use km/h. Speed limits, GPS navigation, and vehicle speedometers switch between these constantly for international travellers.
How many calories are in a kilocalorie?
One kilocalorie (kcal) equals 1,000 small calories. Food nutrition labels use kilocalories but call them "Calories" (capital C) in the US, which causes confusion. When a food label says "200 Calories," it means 200 kcal. The conversion between food calories and other energy units: 1 kcal = 4.184 kJ.
What is a hectare and how does it compare to an acre?
A hectare is 10,000 m² (100 m × 100 m) — the standard metric unit for land area. One hectare equals 2.471 acres. An acre is approximately 4,047 m². Agricultural land in the US is typically measured in acres; most other countries use hectares.
Convert Any Unit Now
Select a category and convert between hundreds of units — length, weight, temperature, volume, speed, area, data storage, and more. Free, no signup, instant results.
Open Unit Converter