Unit Converter Online – Free Length, Weight, Volume & Temperature Converter
Convert any unit in seconds — length, weight, volume, temperature and speed. Enter a value, choose the From and To units, and get a precise result instantly. Built on international standard conversion factors, supporting both metric and imperial systems, with no sign-up and no download.
What Is a Unit Converter?
A Unit Converter is a free online tool that transforms a value from one unit of measurement into another. Whether you are converting centimeters to inches for a DIY project, kilograms to pounds for a recipe, liters to gallons for a road trip, or Celsius to Fahrenheit for a weather forecast, this tool does it in a fraction of a second with professional accuracy.
This converter covers the five most-used measurement categories — length, weight, volume, temperature and speed — across both the metric and imperial systems. Every conversion is computed locally on your device using official international standard factors, so the results are reliable and your data never leaves your browser.
How to Use the Unit Converter
Converting units takes only three quick steps:
- Pick a category. Tap Length, Weight, Volume, Temperature or Speed to load the relevant units.
- Enter a value. Type the number you want to convert in the value field.
- Choose From and To units. Select the starting and target units, then hit “Convert” — or use the swap button to reverse the direction instantly.
For even faster conversions, tap any quick-select chip (such as “cm → in” or “°C → °F”) to fill in both units automatically, then just type your value.
How Does the Unit Converter Work?
Every category uses a built-in table of international standard conversion factors, anchored to a base unit:
Length & Weight & Volume & Speed
result = (value × factor[from]) ÷ factor[to]
For example, to convert 1 meter to feet, the tool divides by the meter factor and multiplies by the foot factor: 1 m ÷ 1 × 3.28084 = 3.28084 ft.
Temperature
Temperature uses a dedicated offset formula because the scales do not share a zero point:
°F = °C × 9/5 + 32 | °C = (°F − 32) × 5/9 | K = °C + 273.15
This guarantees that temperature conversions are exact at every value, including freezing and boiling points.
Precision
Results are formatted with smart precision — compact for everyday values and up to 8 decimal places for tiny or huge numbers — so you always get a clear, usable answer.
Key Features of Our Unit Converter
- 5 categories — length, weight, volume, temperature and speed in one tool.
- Metric & imperial — switch freely between mm/cm/m and inch/ft/yd/mile, or kg and lb.
- Bidirectional conversion — swap From/To with one click.
- High precision — accurate to 8 decimal places when needed.
- Quick-select chips — one-tap access to the most common conversions.
- 100% private — all math happens locally; nothing is uploaded or stored.
- Fully responsive — works smoothly on phones, tablets, and desktops.
Common Use Cases
Travel & Everyday Life
Convert kilometers to miles on a road trip, or liters to gallons at a fuel pump, without fumbling with phone calculators.
Cooking & Recipes
International recipes use grams, cups or fluid ounces. Convert measurements instantly to follow any recipe with confidence.
School & Study
Students solve physics, math and science homework that mixes metric and imperial units. The tool checks answers in seconds.
Work & Engineering
Engineers, builders and designers routinely switch between millimeters and inches, or square meters and square feet.
Frequently Asked Questions
What is a Unit Converter?
A Unit Converter is a free online tool that instantly converts values between different units of measurement, such as length (meters to feet), weight (kg to pounds), volume (liters to gallons), temperature (Celsius to Fahrenheit) and speed. It supports both metric and imperial systems with high precision.
How do I use this Unit Converter?
Choose a category (Length, Weight, Volume, Temperature or Speed), enter a value, then pick the From and To units. The converted result appears instantly. You can also use the swap button to reverse the conversion direction in one click.
Which units are supported?
The converter covers common metric and imperial units: length (mm, cm, m, km, inch, foot, yard, mile), weight (mg, g, kg, ounce, pound, stone, ton), volume (ml, liter, cubic meter, tsp, tbsp, fl oz, cup, pint, quart, gallon), temperature (Celsius, Fahrenheit, Kelvin) and speed (m/s, km/h, mph, knot, ft/s).
Is this Unit Converter 100% free to use?
Yes. Our online Unit Converter is completely free for unlimited use. There are no hidden fees, no premium limits, no registration and no download required.
Does this converter store my data?
No. All conversions are computed locally in your browser using built-in international standard conversion factors. We do not upload, store or share any of your input data, ensuring full privacy.
Are the conversion results accurate?
Yes. The tool uses official international standard conversion coefficients (such as SI base units) and dedicated offset formulas for temperature. Results can be displayed with up to 8 decimal places for maximum precision.
Can I use this Unit Converter on my phone?
Absolutely. The tool is fully responsive and works smoothly on mobile, tablet and desktop devices, making it easy to convert units anywhere, anytime.
What is the difference between Celsius and Fahrenheit?
Celsius and Fahrenheit are two temperature scales. Water freezes at 0°C (32°F) and boils at 100°C (212°F). To convert: F = C × 9/5 + 32, and C = (F − 32) × 5/9. Our converter handles this automatically.