About This Tool
Unit conversions are a daily necessity for recipes, study, travel, and general planning. This Unit Converter handles length, weight, temperature, and volume with metric, selected US customary, and selected UK-associated units such as stones.
Select a measurement category, enter your value, choose the source and target units, and get a rounded conversion. Length covers meters, feet, inches, kilometers, miles, centimeters, and yards. Weight includes kilograms, pounds, ounces, grams, metric tonnes, and stones. Temperature converts Celsius, Fahrenheit, and Kelvin. Volume uses liters and milliliters alongside US customary gallons, cups, pints, quarts, tablespoons, and teaspoons; it does not provide UK imperial volume units.
Temperature conversion deserves special mention because it uses a different mathematical relationship than simple ratio-based conversions. Converting between Celsius and Fahrenheit involves both multiplication and an offset, while Kelvin conversions add or subtract 273.15. The calculator handles all of these formulas automatically, so you never need to remember the conversion equations.
Use the result as a convenience conversion and preserve enough significant figures for the task. Rounded display values may not be appropriate for regulated, laboratory, engineering-tolerance, or safety-critical work.
Key Features
- Four measurement categories: length, weight, temperature, and volume with dozens of unit options
- Labels metric tonnes and US customary volume units explicitly to avoid ambiguous ton, gallon, cup, pint, and quart conventions
- Special temperature conversion handling for Celsius, Fahrenheit, and Kelvin relationships
- Category quick-select buttons for fast switching between measurement types
- Results displayed to four decimal places for convenience; retain source precision for technical work
How this tool works
Methodology reviewed 2026-07-11For length, mass, and volume, the converter divides by the source unit's factor relative to a category base unit and multiplies by the target factor. Temperature is converted to Celsius and then from Celsius to the selected target scale. Output is rounded to four decimal places. The stored ton factor represents metric tonnes, and the listed gallon, cup, pint, quart, tablespoon, and teaspoon factors are US customary liquid units.
Worked example
One metre converts to approximately 3.28084 feet because the international foot is exactly 0.3048 metre. Temperature differs: 0 degrees Celsius converts to 32 degrees Fahrenheit using both a scale and an offset.
How to interpret it: Select the physical quantity before choosing units. Converting a liquid cup to grams requires ingredient density and is not a pure volume conversion, while US and imperial gallons are distinct units.
Assumptions
- Supported conversion factors follow the definitions documented by the tool.
- Input and output refer to the same physical quantity.
- Rounding is for display and not a statement of measurement uncertainty.
Limitations
- The tool does not infer density, reject temperatures below absolute zero, or convert between mass and volume.
- The interface does not provide imperial gallons or US short tons; similarly named regional units must not be substituted.
Sources
Sources explain the standard or planning method; they do not endorse Free Toolset or verify individual results.
Frequently Asked Questions
What systems does this converter cover?
It includes SI or metric units plus selected US customary units and stones. US customary and UK imperial volume measures are not interchangeable, so the volume labels explicitly identify the included cups, pints, quarts, and gallons as US units.
How do I convert Fahrenheit to Celsius?
Subtract 32 from the Fahrenheit temperature, then multiply by 5/9. For example, 72F: (72 - 32) x 5/9 = 22.2C. This converter performs the calculation automatically, including the reverse direction and Kelvin conversions.
Why are there so many different volume measurements?
Different volume units evolved for different purposes. Liters and milliliters are standard in science and most countries. Cups, tablespoons, and teaspoons are common in American cooking. Gallons are used for fuel and large liquid quantities. Pints and quarts bridge the gap between cooking and larger volumes.