The complete online unit converter
A unit converter turns a measurement expressed in one unit into its equivalent in another — for example kilometres into miles, kilograms into pounds, or Celsius into Fahrenheit. This free tool converts across 12 categories and more than 70 units, covering metric (SI), imperial and US customary systems. Every result is calculated from the exact internationally-agreed definition of each unit, so the answers are accurate to about 15 significant figures.
Type a value and the conversion happens in real time. You can swap units, view the formula and step-by-step working, generate a conversion table, set your own decimal precision, and save conversions to history or favorites — all privately in your browser.
Quick answers
Common conversions, answered directly.
How many meters are in a kilometer?
1 kilometer equals 1,000 meters.
What is 5 kilometers in meters?
5 kilometers equals 5,000 meters.
How many pounds is 1 kilogram?
1 kilogram equals about 2.205 pounds.
What is 100°C in Fahrenheit?
100 degrees Celsius equals 212 degrees Fahrenheit.
How many feet are in a mile?
There are 5,280 feet in 1 mile.
How many bytes are in a gigabyte?
1 gigabyte equals 1,000,000,000 bytes (decimal) or 1,073,741,824 bytes (binary GiB).
How fast is 60 mph in km/h?
60 miles per hour equals about 96.56 kilometers per hour.
How many liters are in a US gallon?
1 US gallon equals 3.785 liters.
How to convert units in 3 steps
Pick a category & units
Choose a measurement type (length, weight, temperature…), then select the “from” and “to” units.
Enter your value
Type any number — decimals and scientific notation like 1e6 are supported. The result appears instantly.
Read, copy or save
View the formula, table and all-unit breakdown, then copy, share, download or star the conversion.
Everything in one converter
Real-time conversion
Results update the instant you type — no convert button, no waiting.
One-click swap
Reverse the conversion direction instantly to check a value both ways.
Formula & steps
See the exact formula and a step-by-step breakdown for every conversion.
Smart unit search
Find any unit across all 12 categories by name or symbol in one search box.
History & favorites
Your last 50 conversions and starred pairs are saved privately in your browser.
Precision control
Choose 0–10 decimals or auto, with scientific notation for huge or tiny numbers.
100% private
Everything runs on your device. Nothing is uploaded — it even works offline.
Conversion tables
Auto-generated reference tables and full all-unit breakdowns for any value.
Supported measurement categories
Jump straight to any category.
Measurement units explained
- Metre (m)
- The SI base unit of length, defined by the speed of light in a vacuum. One metre is about 3.28 feet.
- Kilometre (km)
- One thousand metres. Commonly used for road distances in most of the world; 1 km ≈ 0.621 miles.
- Mile (mi)
- An imperial unit of length equal to 1,609.344 metres or 5,280 feet, used mainly in the United States and the United Kingdom.
- Kilogram (kg)
- The SI base unit of mass. One kilogram equals about 2.205 pounds and is the everyday unit of weight in metric countries.
- Pound (lb)
- An imperial unit of mass equal to exactly 0.45359237 kilograms, divided into 16 ounces.
- Celsius (°C)
- A temperature scale where water freezes at 0° and boils at 100° at sea level. Used by most of the world.
- Fahrenheit (°F)
- A temperature scale where water freezes at 32° and boils at 212°. Used mainly in the United States.
- Kelvin (K)
- The SI base unit of temperature, starting at absolute zero (−273.15 °C). It uses the same degree size as Celsius.
- Litre (L)
- A metric unit of volume equal to one cubic decimetre (1,000 cm³). One litre is about 0.264 US gallons.
- Byte (B)
- A unit of digital information equal to 8 bits, typically storing a single character of text.
- Pascal (Pa)
- The SI unit of pressure, equal to one newton per square metre. Atmospheric pressure is about 101,325 Pa.
- Watt (W)
- The SI unit of power, equal to one joule per second. A kilowatt is 1,000 watts.
Where you will use it
Travel & driving
Convert road distances and speed limits between kilometres and miles, or km/h and mph, when driving or planning trips abroad.
Cooking & recipes
Switch recipe amounts between millilitres, cups, grams and ounces so international recipes work with your measuring tools.
Fitness & health
Convert body weight between kilograms, pounds and stones, and food energy between kilocalories and kilojoules.
Construction & DIY
Move between metres, feet, centimetres and inches for measuring rooms, lumber and materials.
Computing & storage
Compare file and drive sizes across megabytes, gigabytes and terabytes — in both decimal and binary standards.
Science & engineering
Convert pressure (Pa, bar, psi, atm), energy (J, cal, kWh), power (W, hp) and angles (degrees, radians) for technical work.
Accuracy & precision
Conversions use exact unit definitions (for example 1 inch = 0.0254 m, 1 pound = 0.45359237 kg, 1 US gallon = 3.785411784 L) and are computed with double-precision arithmetic — roughly 15 significant digits. For values beyond the quadrillions or smaller than a millionth, the converter automatically switches to scientific notation so no precision is hidden. Temperature uses the proper offset formulas rather than a single multiplier, and digital storage offers both decimal (KB, MB, GB) and binary (KiB, MiB, GiB) standards.
Frequently asked questions
How many meters are in a kilometer?
There are exactly 1,000 metres in one kilometre. The prefix “kilo” means one thousand, so 1 km = 1,000 m and, conversely, 1 m = 0.001 km.
How do I convert kilometers to meters manually?
Multiply the number of kilometres by 1,000. For example, 5 km × 1,000 = 5,000 m. To go the other way, divide metres by 1,000.
How do I convert Celsius to Fahrenheit?
Use the formula °F = (°C × 9 / 5) + 32. For example, 20 °C × 9 / 5 = 36, plus 32 = 68 °F. Temperature is an offset scale, so you cannot simply multiply by a single factor.
How many pounds are in a kilogram?
One kilogram equals about 2.2046 pounds (2.20462262 lb). To convert kilograms to pounds, multiply by 2.2046; to convert pounds to kilograms, multiply by 0.453592.
Is this unit converter accurate?
Yes. Every conversion uses the exact internationally-agreed definition of each unit (for example 1 inch = 0.0254 m and 1 pound = 0.45359237 kg) and is computed to about 15 significant figures. You can also set the decimal precision yourself.
Can I convert very large or very small numbers?
Yes. The converter accepts scientific notation such as 1e6 (one million) or 1.5e-9, handles values into the quadrillions, and automatically switches to scientific notation for extreme magnitudes so results stay readable and precise.
Does the converter support decimal numbers?
Absolutely. You can enter decimals (for example 2.54), choose how many decimal places to display (0 to 10), and the converter rounds the displayed result without losing internal precision.
What is the difference between a kilobyte (KB) and a kibibyte (KiB)?
A kilobyte uses the decimal standard: 1 KB = 1,000 bytes. A kibibyte uses the binary standard: 1 KiB = 1,024 bytes. Storage marketing usually uses decimal units, while operating systems often report binary units. Both are available in the Data Storage category.
How do I swap the “from” and “to” units?
Click the ⇄ Swap button between the two unit boxes. It instantly reverses the conversion direction and recalculates the result — handy for checking a value both ways.
Are my conversions saved or sent to a server?
No data ever leaves your browser. Conversions run entirely on your device, and your history and favorites are stored locally in your browser only — nothing is uploaded.
How does conversion history work?
Your most recent conversions (up to 50) are saved in your browser’s local storage. Click any entry to reload it instantly, or clear the list at any time. History stays private to your device.
Can I save my favorite conversions?
Yes. Star any conversion — such as km → miles or °C → °F — to pin it to your Favorites for one-click access on future visits. Favorites are stored locally in your browser.
What measurement categories are supported?
Length, weight/mass, area, volume, temperature, speed, time, digital data storage, energy, pressure, power and angle — covering metric (SI), imperial and US customary units in one tool.
How many feet are in a mile?
There are exactly 5,280 feet in one mile. A mile is defined as 1,609.344 metres and a foot as 0.3048 metres, so 1,609.344 ÷ 0.3048 = 5,280.
How do I convert miles per hour to kilometers per hour?
Multiply miles per hour by 1.609344. For example, 60 mph × 1.609344 ≈ 96.56 km/h. To convert km/h to mph, multiply by 0.621371.
Is the unit converter free to use?
Yes, it is completely free with no sign-up, no install and no usage limits. It works on desktop and mobile, and even offline once the page has loaded.
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