Kilometres to miles (distance)
Input
10 kmOutput
6.2137 milesUse for road trips, running events, and international directions. Exact factor: 1 mile = 1.609344 km.
Convert between metric and imperial units instantly — kilometres to miles, kg to lbs, Celsius to Fahrenheit, litres to gallons, and more. Accurate, fast, and free.
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Free energy unit converter — convert joules, calories, kilocalories (kcal), kilowatt-hours, BTU, and electronvolts. Supports both food energy and physics units. No signup.
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Free power converter — convert watts, kilowatts, megawatts, horsepower (mechanical and metric), and BTU/hr. Useful for electrical and mechanical engineering. No signup.
Free pressure converter — convert between PSI, bar, pascal, kilopascal, megapascal, and atmospheres. Useful for plumbing, engineering, and tire pressure. No signup required.
Free speed converter — convert between km/h, mph, m/s, ft/s, knots, and Mach. Enter any speed and see all conversions instantly. Supports metric and imperial. No signup.
Free temperature converter — instantly convert between Celsius, Fahrenheit, and Kelvin. See all three temperature values update in real time as you type. No signup required.
Free volume converter — convert between liters, milliliters, gallons (US and UK), fluid ounces, cups, pints, quarts, and cubic meters. No signup required.
Free weight converter — convert between kilograms, pounds, grams, ounces, stones, and metric tons. See all conversions at once as you type. Metric and imperial. No signup.
A free online unit converter lets you convert between length, weight, temperature, volume, speed, data size, energy, and pressure units instantly in your browser. The most common conversions include kilometres to miles, kilograms to pounds, Celsius to Fahrenheit, and MB to GB. All converters use exact conversion factors (not rounded values), work on any device, and require no account. Enter a value, choose your units, and get the result in one click.
Choose a unit converter
Select the measurement type — length, weight, temperature, speed, volume, and more.
Enter your value
Type the number you want to convert in the input field.
Select your units
Choose the unit you are converting from and the unit you are converting to.
Read the result
The converted value appears instantly. Use the swap button to reverse the conversion.
A free online unit converter is a browser-based tool that converts values between different systems of measurement — the metric system (SI), the US customary system, and the imperial system. You enter a number, choose your source unit and target unit, and the converted value appears instantly.
Unit converters are essential because the world uses two major measurement systems that don't naturally translate to each other. The metric system (used by most of the world) uses metres, kilograms, litres, and Celsius. The US customary system uses miles, pounds, gallons, and Fahrenheit. The imperial system (historically used in the UK) is similar but not identical.
The converters on this site use exact conversion factors, not rounded approximations. For example, 1 mile is exactly 1.609344 km, and 1 pound is exactly 0.45359237 kg. This matters in engineering, science, cooking, and any context where small differences accumulate over many conversions.
Use a unit converter whenever you encounter a measurement in an unfamiliar system. These are the most frequent real-world scenarios:
Length conversion is the most commonly needed unit conversion. The key conversions to know:
The Length Converter shows your input converted to all common units simultaneously, so you can see the equivalent in metres, kilometres, miles, feet, inches, and centimetres at once — useful when you need the same distance in multiple contexts.
For running and cycling: 5 km = 3.11 miles, 10 km = 6.21 miles, 21.1 km (half marathon) = 13.1 miles, 42.2 km (marathon) = 26.2 miles.
Weight conversion between the metric and imperial systems is needed daily for fitness, cooking, shipping, and international product listings. The essential conversion factors:
Common weight conversions in practice:
The Weight Converter on this site supports all of these units plus metric tonnes, short tons, and long tons.
Temperature is one of the trickier conversions because the scales have different zero points, requiring a formula rather than a simple multiplication factor.
Conversion formulas:
Useful reference temperatures:
Kelvin is used in science and engineering where negative temperatures are impossible — absolute zero (0 K) is −273.15°C, the lowest possible temperature.
Data storage units are a frequent source of confusion because two different systems exist side by side: the decimal (SI) system and the binary system.
This is why a "1 TB" hard drive shows as roughly 930 GB in Windows and macOS — the drive uses decimal gigabytes, but the OS reports binary gibibytes.
Common data size references:
The Data Converter handles both decimal and binary prefixes and makes the distinction clear.
Pick a converter, enter your value, and get the result in one click. Works on desktop and mobile.
No signup required · Exact conversion factors · 100% free
A unit converter converts a value from one measurement unit to another (metric, imperial, or US customary) using exact conversion factors and formulas.
A unit converter is a tool that translates measurements between different unit systems — for example, kilometres to miles, kilograms to pounds, Celsius to Fahrenheit, litres to gallons, and square metres to square feet. Converters matter because different countries and industries use different standards, and small conversion errors can cause real mistakes in shipping, engineering, cooking, and travel.
This unit converter hub helps you pick the right converter for the measurement type you’re dealing with, then converts accurately using standard factors (and formulas for temperature).
Choose a category: length, weight, temperature, area, volume, speed, or others.
Type the number you want to convert in the input field and select the source unit from the dropdown.
The tool shows your value converted to all common units in the selected category simultaneously.
For units with multiple definitions (e.g., US vs UK gallon), select the exact unit you need before copying the result.
Common real-world scenarios where this tool saves time.
Convert cups to millilitres, ounces to grams, and Fahrenheit to Celsius when using recipes from different countries.
Convert miles to kilometres, pounds to kilograms, and Fahrenheit to Celsius when travelling internationally.
Convert between SI and imperial units for measurements used in technical documentation, specifications, and calculations.
Convert clothing sizes and measurements between US, UK, and European standards when buying internationally.
Convert square feet to square metres and acres to hectare when reviewing international property listings.
Convert km/h to mph and fuel volume units when comparing vehicle specs across regions.
Input
10 kmOutput
6.2137 milesUse for road trips, running events, and international directions. Exact factor: 1 mile = 1.609344 km.
Input
70 kgOutput
154.3236 lbsUseful for fitness tracking, luggage limits, and shipping labels. Exact factor: 1 lb = 0.45359237 kg.
Input
200°COutput
392°FTemperature uses a formula (not a multiplier): °F = (°C × 9/5) + 32.
Most unit conversions use a fixed multiplier (and sometimes an additive offset). This hub relies on internationally standardized definitions (SI and agreed exact constants) and uses formulas for non-linear scales like temperature.
Likely cause: Different rounding rules or unit definitions (US vs UK gallon, metric vs mechanical horsepower, etc.).
Fix: Check the exact unit variant and increase displayed precision before rounding.
Likely cause: Offset was missed (32°F) or wrong direction was applied.
Fix: Use the temperature converter and verify the formula: °F = (°C × 9/5) + 32; °C = (°F − 32) × 5/9.
Likely cause: Some converters show only a single target unit.
Fix: Use category converters that show all common units simultaneously for faster comparison.
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Conversions use exact standard factors where defined (for example, 1 inch = 2.54 cm exactly, 1 mile = 1.609344 km exactly, and 1 lb = 0.45359237 kg exactly). Results are then displayed with rounding, but the underlying calculation maintains high precision.
No. Conversions run locally in your browser — the values you enter are not uploaded.
Yes. Temperature conversions use formulas (not just multiplication): °F = (°C × 9/5) + 32, °C = (°F − 32) × 5/9, and K = °C + 273.15.
They overlap but are not identical. For example, a US gallon is 3.78541 litres while a UK imperial gallon is 4.54609 litres. Always choose the correct unit variant for your region and context.
Multiply kilometres by 0.621371 to get miles. For the reverse, multiply miles by 1.609344 to get kilometres.
Multiply kilograms by 2.20462 to get pounds. For the reverse, multiply pounds by 0.45359237 to get kilograms.
First choose the gallon type: US gallon (1 gal = 3.78541 L) or UK gallon (1 imp gal = 4.54609 L). Then divide litres by the appropriate constant.
Different tools round at different steps. To avoid discrepancies, keep more decimal places during calculation and round only the final displayed value.
Yes. Use the Area Converter for square units (sq ft, sq m, acres, hectares) and the Volume Converter for litres, gallons, cups, and fluid ounces.
Yes — completely free with no signup and no usage limits.
Runs locally in your browser — no uploads and no signup required.
Uses exact unit definitions and internationally standardized conversion factors. Temperature conversions use the correct formulas (offset + scaling).
For regulated engineering, medical, or safety-critical use, verify requirements and rounding rules for your specific standard or jurisdiction.
Part of Unit Converters
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