Unit Converter
Convert between length, weight, temperature, speed, area, and volume units.
How to Use the Unit Converter
The Unit Converter supports six categories of measurement with dozens of units. Select a category from the tabs, choose your source and target units from the dropdowns, enter a value in either field, and see the conversion instantly. The conversion is bidirectional — change either value to update the other.
Categories Available
- Length: Millimeters, centimeters, meters, kilometers, inches, feet, yards, miles, nautical miles
- Weight: Milligrams, grams, kilograms, metric tons, ounces, pounds, stones, US tons
- Temperature: Celsius, Fahrenheit, Kelvin, Rankine (using exact formulas)
- Speed: Meters/second, km/h, mph, knots, feet/second
- Area: mm², cm², m², km², in², ft², yd², acres, hectares
- Volume: Milliliters, liters, m³, fluid ounces, cups, pints, quarts, gallons
Temperature Conversions
Temperature conversions require special formulas (not simple multiplication). The converter handles Celsius↔Fahrenheit↔Kelvin↔Rankine using the exact international formulas. Celsius is used as the intermediate unit for conversions not involving Celsius directly.
Bidirectional Conversion
Type in either the "From" or "To" input field and the other updates automatically. Use the swap button (⇄) to quickly reverse the direction of conversion while keeping the current numeric value. This is useful when you know the result and want to find the source.
Related Tools
Frequently Asked Questions
How accurate are the conversions?
All conversions use precise, internationally standardized conversion factors. Length and weight conversions are exact (based on SI definitions). Temperature formulas are exact. Area and volume conversions are exact. Results are computed using JavaScript floating-point arithmetic, accurate to about 15 significant digits for most unit ranges.
Why does temperature conversion work differently?
Temperature conversions are non-linear — they require adding or subtracting an offset — unlike all other unit conversions which are pure ratios. The tool converts via Celsius as the intermediate: °F = (°C × 9/5) + 32, K = °C + 273.15, °R = °F + 459.67.
What is a nautical mile?
A nautical mile is a unit of length used in navigation, originally based on one minute of arc of latitude. It equals exactly 1,852 meters (about 1.151 statute miles). Knots (nautical miles per hour) are the corresponding speed unit used in maritime and aviation navigation.
How many milliliters are in a gallon?
One US gallon equals 3,785.41 milliliters (approximately 3.785 liters). The UK imperial gallon is larger: 4,546.09 ml. This converter uses US gallon measurements, which are the most commonly used internationally for online unit conversion purposes.