Convert units of measurement instantly
Converting between units is one of those tasks that comes up constantly — in cooking, travel, fitness, DIY, science homework and international shipping — and getting it wrong can be more than a minor nuisance. This free unit converter turns one unit into another in real time across length, weight and temperature. Choose a category, pick your "from" and "to" units, type a value, and read the result immediately. A swap button reverses the conversion in one click, and everything runs privately in your browser.
What you can convert
- Length — millimetres, centimetres, metres, kilometres, inches, feet and miles.
- Weight — grams, kilograms, tonnes, pounds and ounces.
- Temperature — Celsius, Fahrenheit and Kelvin.
These three categories cover the conversions most people need day to day, whether you are following a recipe from another country, planning a trip, tracking a workout or helping a child with science.
Metric and imperial in one place
Most of the world uses the metric system, while a handful of countries — most notably the United States — rely on imperial units for everyday measurements. That split is precisely why conversion comes up so often. A recipe calls for ounces when your scale reads grams; a road sign shows miles when your car's habit is kilometres; a weather forecast is in Fahrenheit when you think in Celsius. Having length, weight and temperature together in a single tool means you never have to hunt for a different converter depending on the task.
The most popular conversions
A few conversions are searched for far more than any others, and they are all here: kilometres to miles and back for distance; kilograms to pounds for body weight and shipping; Celsius to Fahrenheit for weather and cooking; and centimetres to inches or feet to metres for height and dimensions. Because the converter works both ways, you can go in whichever direction you need simply by choosing the units or tapping swap.
Why the results are reliable
Accuracy matters, so every unit in the tool is defined relative to a base unit — the metre for length, the kilogram for weight, and degrees Celsius for temperature — using standard, internationally agreed conversion factors. For example, one inch is defined as exactly 0.0254 metres, and one pound as about 0.4536 kilograms. Converting through a common base keeps chained conversions consistent and precise, and results are rounded to a sensible number of significant figures so they stay readable without losing meaningful accuracy.
Temperature is a little different
Length and weight conversions are simple multiplications, but temperature is worth a note because it involves an offset, not just a scale. Celsius and Fahrenheit have different zero points, which is why the formula is °F = °C × 1.8 + 32 rather than a plain multiplication. Kelvin shares Celsius's scale but starts at absolute zero, so converting to it means adding 273.15. The tool handles all of this for you, so you never have to remember which formula applies.
How to use it
Select a category, choose the units you are converting between, and enter your number. The result appears at once and updates as you type, and the swap button flips the direction instantly. Because it all happens on your device, the converter is fast, private and works offline once the page has loaded — a dependable everyday helper for any measurement you need to translate.
A quick reference for everyday conversions
While the tool does the exact maths for you, it helps to carry a few rough conversions in your head for quick sanity checks. For distance, one mile is about 1.6 kilometres, and a kilometre is roughly six-tenths of a mile, so a 5 km run is a little over three miles. For weight, one kilogram is about 2.2 pounds, which means a 70 kg person weighs around 154 pounds. For everyday lengths, one inch is 2.54 centimetres and one foot is just over 30 centimetres. Temperature is the trickiest to estimate because of its offset, but a useful anchor is that 0°C is 32°F (freezing) and 100°C is 212°F (boiling), while a comfortable room at 20°C is 68°F. Cooking conversions come up constantly too: 250 grams is roughly half a pound, and an oven at 180°C is about 350°F. These approximations will never replace an exact converter for anything important, but they let you catch obvious errors and make sense of foreign measurements at a glance — and when precision matters, the tool above has you covered.
Frequently asked questions
What units can I convert?
The tool covers length (mm, cm, m, km, inches, feet, miles), weight (grams, kilograms, tonnes, pounds, ounces) and temperature (Celsius, Fahrenheit, Kelvin).
How do I convert kilometres to miles?
Choose the Length category, set 'from' to kilometres and 'to' to miles, then type a value. One kilometre is about 0.621 miles, and the exact figure appears instantly.
How do I convert Celsius to Fahrenheit?
Select Temperature, then Celsius to Fahrenheit. The formula is °F = °C × 1.8 + 32, and the tool applies it automatically.
Are the conversions accurate?
Yes. They use internationally defined factors, such as 1 inch equalling exactly 0.0254 metres, with results rounded for readability.