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Free Unit Converter
Convert values within length, area, volume, mass, and temperature families with explicit source and destination units. Conversion never crosses dimensions and temperature uses affine formulas rather than a simple multiplier.
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What this tool is for
Convert values within length, area, volume, mass, and temperature families with explicit source and destination units. Conversion never crosses dimensions and temperature uses affine formulas rather than a simple multiplier.
How to use
- Choose the measurement family.
- Enter a numeric value and select compatible source and destination units.
- Review the full-precision result and round only for the receiving task.
Example
Convert 2.5 metres to 250 centimetres, or 1 square metre to 10,000 square centimetres without mixing linear and square factors.
FAQ
Why can I not convert litres to kilograms?
That requires a material density, so it is not a pure unit conversion.
Does one decimal precision fit every task?
No. Keep sufficient precision and round according to the target use.
Reproducible examples
Known inputs and expected results
Run these examples in the workspace above and compare the result with the documented output.
Linear length conversion
- Input
- 2.5 metres
- Options
- Convert metres to centimetres.
- Action
- Run the conversion.
- Expected output
- 250 centimetres.
- Explanation
- The length factor is 100 centimetres per metre.
Affine temperature conversion
- Input
- 32 degrees
Fahrenheit - Options
- Convert
FahrenheittoCelsius. - Action
- Run the conversion.
- Expected output
- 0 degrees
Celsius. - Explanation
Temperatureuses (F − 32) × 5/9, not a scale factor alone.
Error or unsupported case
Cross-dimension request
- Input
- 1 litre to kilograms
- Expected error or limit
- Volume cannot be converted to mass without material density.
- Safer alternative
- Choose units from one dimension or use a domain calculator with an explicit density.
When not to use this tool
- Calibrated legal metrology
- Currency, density-based, or engineering-tolerance conversion
Algorithm and assumptions
Each family uses fixed factors relative to a base unit; area factors are squared, volume factors cubed, temperature uses affine formulas, and JavaScript floating point sets precision.
Input and output
Input is a number and two compatible units. Output is one converted numeric value and formula context.
Supported formats and behavior
Length, area, volume, mass, and temperature- Metric and selected imperial units
- Negative values where physically meaningful
Limits
- No live currency or density-based conversion
- Displayed floating-point precision may need rounding
Edge cases and common errors
- Area factors are squared
- Volume factors are cubed
- Temperatures below absolute zero are mathematically convertible but physically invalid
Release testing
Checks cover identity, metric/imperial known vectors, area and volume factors, temperatures, invalid input, swap, and reset.
Privacy boundary
The input and result stay in this browser session. ZZP Box does not upload or store the values entered in this tool.
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