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universal Units Converter

universal

Free Unit Converter

Convert length, weight, temperature, volume, area, speed and time — free, instant and entirely in your browser.

✓ Accurate conversions✓ No account needed✓ Nothing uploaded✓ Any device
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Same value in every unit

    Your numbers never leave your browser. Nothing is sent to any server.

    How it works

    Three steps, no account

    Pick a category

    Choose length, mass, temperature, volume, area, speed or time. Each category offers the units people actually use, from metric to US and imperial.

    Enter a value and two units

    Type your number, then choose the unit to convert from and the unit to convert to. The result updates as you type — no button to press, no login, no waiting.

    Read and copy the result

    The converted value appears in large type with the full equation below it. Copy it with one click, change the number of decimal places, or swap the two units.

    Why it matters

    Accurate conversions, every time

    Whether you follow a recipe from another country, check a road sign abroad, size a room or do your homework, a conversion only helps if it is right. A small slip in a factor or a unit mix-up can spoil a dish, a purchase or an assignment.

    The converter uses the exact definitions behind each unit — for example, one inch is exactly 25.4 millimeters and one pound is exactly 0.45359237 kilograms. Every result is calculated from those factors in your browser and shown to up to ten significant digits by default, or to the number of decimal places you choose.

    Use cases

    Where a unit converter helps

    Cooking and recipes

    Turn cups, tablespoons and fluid ounces into milliliters and liters, or ounces and pounds into grams and kilograms.

    Travel

    Understand distances in miles or kilometers, speeds in mph or km/h and temperatures in Fahrenheit or Celsius before you arrive.

    School and study

    Check homework, lab results and physics problems quickly, and see the same value in every unit of a category at once.

    DIY and home projects

    Convert inches, feet and meters, or square feet and square meters, when you plan a room, buy materials or read a plan.

    Fitness and health

    Switch between pounds, kilograms and stone, or between kilometers and miles, for training logs and body-weight tracking.

    100% private

    Your numbers stay on your device. Nothing is uploaded or stored, and once the page has loaded the converter keeps working without a connection.

    Under the hood

    How the conversion works

    Each unit is defined by its size relative to a base unit of its category, such as the meter for length or the kilogram for mass. Your value is first converted to the base unit and then to the target unit, which keeps every pair of units consistent. Temperature is the exception, because the scales have different zero points: Celsius, Fahrenheit and Kelvin are converted with their own formulas through Kelvin. Everything is calculated locally with standard JavaScript numbers and formatted for your language.

    Questions

    Frequently asked questions

    Basics
    Is this unit converter really free?
    Yes. The converter is completely free, with no limit on how many conversions you make. There is no paid tier and no feature locked behind a payment.
    Do I need an account to use it?
    No. There is no sign-up, no login and no account of any kind. Open the page, enter a value and read the result.
    Are my numbers stored or sent anywhere?
    No. Everything happens inside your own browser. The values you type are never uploaded, stored or transmitted to any server. After the page has loaded, the converter works the same even without an internet connection.
    How accurate are the results?
    Results use the exact definitions of the units, such as 25.4 millimeters per inch and 0.45359237 kilograms per pound. By default a result is shown with up to ten significant digits, so the display is far more precise than everyday use requires. For safety-critical work, always check the result against the original source.
    Options & usage
    How do I use the unit converter?
    Choose a category, type a value, then pick the unit to convert from and the unit to convert to. The result appears immediately. Use the swap button to reverse the two units and the copy button to copy the result with its unit.
    Which units are included?
    Length (millimeter to mile and nautical mile), mass (milligram to metric ton, ounce, pound, stone and US ton), temperature (Celsius, Fahrenheit and Kelvin), volume (milliliter to cubic meter, plus US and imperial cooking and liquid units), area (square centimeter to square mile, including hectare and acre), speed (m/s, km/h, mph, knot and ft/s) and time (millisecond to week).
    Can I enter decimals with a comma?
    Yes. You can type 1.5 or 1,5. If a number contains both a dot and a comma, the one that comes last is treated as the decimal separator. Results are displayed with the decimal separator of the page language.
    What does “Decimal places” do?
    By default (Auto) the result is shown with up to ten significant digits and trailing zeros removed. Choose 0, 2, 4 or 6 to round the displayed result to that number of decimal places instead. Rounding affects only what you see and copy.
    Why are temperatures handled differently?
    Celsius, Fahrenheit and Kelvin do not share a zero point, so a simple multiplication is not enough. The converter applies the correct formula for each scale. It also rejects any value below absolute zero, which is 0 K, −273.15 °C or −459.67 °F.
    Privacy & technical
    How are the conversions calculated?
    Your value is converted to a base unit of the category (for example the meter or the kilogram) using the exact factor of the unit you chose, and then converted to the target unit. This runs locally in your browser using standard JavaScript numbers, so tiny rounding differences at the very last digits can occur.
    Why do US and imperial gallons, pints and cups differ?
    They come from different historical systems. A US gallon is 3.785411784 liters, while an imperial gallon is 4.54609 liters. The converter labels each unit as US or imperial so you can choose the one your recipe or product uses.