Unit Converter
Convert between length, weight, volume, temperature, digital storage, speed, area, and time units instantly. Free, private, and unlimited.
What Is Unit Conversion?
Unit conversion is the process of changing a measurement from one unit to another within the same category. Whether you are converting miles to kilometers, pounds to kilograms, or Fahrenheit to Celsius, the underlying math involves multiplying or dividing by a fixed conversion factor. Temperature is the exception, requiring a formula with both multiplication and an offset. This tool handles all of it automatically so you can focus on the answer rather than the arithmetic.
Metric vs Imperial
The metric system (SI) uses base-10 units like meters, kilograms, and liters, making it straightforward to scale between sizes by simply moving the decimal point. The imperial system, still widely used in the United States, uses units like feet, pounds, and gallons with less intuitive relationships (12 inches per foot, 16 ounces per pound, 4 quarts per gallon). When working with international data, scientific research, or recipes from other countries, you will inevitably need to convert between these two systems. This converter supports both, plus specialty categories like digital storage and speed.
Common Conversion Formulas
Here are some of the most frequently used conversion formulas covered by this tool:
| Category | Conversion | Formula / Factor |
|---|---|---|
| Length | Miles ↔ Kilometers | 1 mile = 1.609344 km |
| Length | Inches ↔ Centimeters | 1 inch = 2.54 cm |
| Weight | Pounds ↔ Kilograms | 1 lb = 0.453592 kg |
| Weight | Ounces ↔ Grams | 1 oz = 28.3495 g |
| Volume | Gallons ↔ Liters | 1 US gal = 3.78541 L |
| Volume | Cups ↔ Milliliters | 1 US cup = 236.588 mL |
| Temperature | Fahrenheit ↔ Celsius | °C = (°F − 32) × 5/9 |
| Temperature | Celsius ↔ Kelvin | K = °C + 273.15 |
| Digital Storage | Gigabytes ↔ Megabytes | 1 GB = 1,024 MB |
| Speed | Miles/hour ↔ Km/hour | 1 mph = 1.60934 km/h |
Frequently Asked Questions
How do I convert between metric and imperial units?
Select a category such as Length or Weight, choose a metric unit in the From dropdown and an imperial unit in the To dropdown, then type a value. The converter instantly shows the result along with the conversion formula. You can also use the swap button to reverse the direction.
Why does my hard drive show less storage than advertised?
Hard drive manufacturers use decimal (base-10) definitions where 1 GB equals 1,000,000,000 bytes. Operating systems use binary (base-2) definitions where 1 GB equals 1,073,741,824 bytes. A drive advertised as 500 GB in decimal terms shows about 465 GB in your operating system. Use the Digital Storage category to see the exact difference.
What is the difference between a US cup and a metric cup?
A US customary cup equals 236.588 milliliters, while a metric cup (used in Australia and some other countries) equals exactly 250 milliliters. This converter uses US cups. If a recipe calls for metric cups, you can convert by entering the metric cup value in milliliters (250 ml per cup) and converting to your desired unit.
How do I convert Fahrenheit to Celsius?
The formula is: °C = (°F − 32) × 5/9. For example, 72°F equals (72 − 32) × 5/9 = 22.22°C. Select the Temperature category in this converter, choose Fahrenheit as the From unit and Celsius as the To unit, then type any temperature value to see the result instantly.
Is this unit converter free to use?
Yes. This unit converter is completely free with no sign-ups, no accounts, and no usage limits. It runs entirely in your browser, so no data is sent to any server. You can convert as many values as you want across all eight categories.