Convert length, weight, temperature and more — free, fast, private.
What is a unit converter?
A unit converter translates a measurement expressed in one unit into the equivalent value in
another unit of the same quantity — for example miles into kilometers, pounds into kilograms, or
Fahrenheit into Celsius. This tool covers seven everyday categories: length, weight, temperature,
area, volume, speed and digital storage. It runs entirely in your browser, so results appear
instantly as you type and nothing you enter is ever sent to a server.
How to use this tool
- Pick a category such as Length or Temperature.
- Type the value you want to convert.
- Choose the from and to units — the result updates live.
- Use Swap units to reverse the direction, and Copy result to copy it.
Common conversion factors
The reference table below lists the conversions people look up most often. Length, weight, area,
volume, speed and data units are exact multiples of a base unit; temperature uses offset formulas
instead (see the FAQ).
| Quantity | Conversion | Equals |
|---|
| Length | 1 inch (in) | 2.54 centimeters (cm) |
| Length | 1 foot (ft) | 0.3048 meters (m) |
| Length | 1 mile (mi) | 1.609 kilometers (km) |
| Length | 1 yard (yd) | 0.9144 meters (m) |
| Weight | 1 kilogram (kg) | 2.2046 pounds (lb) |
| Weight | 1 pound (lb) | 0.4536 kilograms (kg) |
| Weight | 1 ounce (oz) | 28.3495 grams (g) |
| Temperature | 0 °C | 32 °F = 273.15 K |
| Temperature | 100 °C | 212 °F = 373.15 K |
| Area | 1 acre (ac) | 4046.86 square meters (m²) |
| Area | 1 hectare (ha) | 10,000 square meters (m²) |
| Volume | 1 US gallon (gal) | 3.7854 liters (L) |
| Volume | 1 US cup | 236.588 milliliters (mL) |
| Speed | 1 mile per hour (mph) | 1.609 kilometers per hour (km/h) |
| Speed | 1 knot (kn) | 1.852 kilometers per hour (km/h) |
| Data storage | 1 kilobyte (KB) | 1024 bytes (B) |
| Data storage | 1 megabyte (MB) | 1024 kilobytes (KB) |
Common mistakes to avoid
- Mixing up ounces. The Weight category uses the ounce (oz), a unit of mass (28.3495 g). The Volume category uses the US fluid ounce (fl oz), a unit of capacity (29.5735 mL). One fluid ounce of water weighs about 1.04 oz, not exactly 1 oz, so always confirm which category you are in before converting.
- Confusing bits and bytes. File sizes are measured in bytes, network speeds in bits. In Data storage, 1 byte equals 8 bits, so a 100 Mbit per second connection transfers at most 12.5 megabytes per second.
- Assuming imperial gallons. Every volume unit here is US customary: 1 US gallon is 3.785 liters. A UK imperial gallon is 4.546 liters, roughly 20 percent larger, so results will not match UK fuel economy figures.
A quick accuracy check
Want to sanity-check any converter? Convert -40 from Celsius to Fahrenheit: the result must be exactly -40, the only temperature where the two scales meet. Then convert 0 Kelvin to Celsius: you should get -273.15, absolute zero. A converter that handles both edge cases correctly has sound temperature formulas, and this one does.
Frequently asked questions
What is the difference between metric and imperial units?
The metric system (meters, kilograms, liters) is decimal: every unit is a power-of-ten multiple of a base unit, which makes conversions simple. Imperial and US customary units (inches, pounds, gallons) use historical ratios such as 12 inches per foot or 16 ounces per pound. This tool handles both systems and converts freely between them.
Why is temperature conversion different from other units?
Most units only need multiplication by a factor, but Celsius and Fahrenheit scales also have different zero points (offsets). That is why converting them needs a formula: °F = °C × 9/5 + 32, and °C = (°F − 32) × 5/9. Kelvin starts at absolute zero, so K = °C + 273.15. This tool applies the correct formula automatically.
How precise are the conversion results?
Conversions use exact or standard-defined factors (for example 1 inch is exactly 2.54 cm) computed in double precision, and the displayed result is rounded to at most 6 significant digits, which is more than enough for everyday, cooking, travel and study use. Data storage units use binary multiples: 1 KB = 1024 bytes.
Is this unit converter free?
Yes. The tool is completely free, requires no sign-up, and has no usage limits. All calculations run locally in your browser, so your numbers never leave your device.