UnitConversion

An expansible unit conversion library for .NET: exact definitions, synonym-based unit names and no dependencies.

Install

dotnet add package UnitConversion

The package targets .NET Standard 2.0, .NET 8 and .NET 10. That covers .NET Framework 4.6.1 and later, .NET Core 2.0 and later, and every current .NET release. It has no dependencies.

Quick start

using UnitConversion;

var kgToLbs = new MassConverter("kg", "lbs");

double pounds = kgToLbs.LeftToRight(452);        // 996.4894...
double kilograms = kgToLbs.RightToLeft(pounds);  // 452
double rounded = kgToLbs.LeftToRight(452, 2);    // 996.49

Unit names ignore case, and each unit answers to several names (kg, kilogram, lb, lbs, pound, pounds). The converter converts between its left and right unit in both directions, and you can change either unit at any time:

kgToLbs.UnitLeft = "stone";
kgToLbs.UnitRight = "kg";
double kg = kgToLbs.LeftToRight(12);             // 76.2035...

What it converts

Converter	Quantity	Some of its units
DistanceConverter	length	m, km, cm, mm, in, ft, yd, mile, nautical mile, au, light year
MassConverter	mass	kg, g, mg, tonne, lb, oz, stone, short ton, long ton, carat
AreaConverter	area	m², km², ha, acre, ft², yd², mi²
VolumeConverter	volume	l, ml, m³, ft³, US and imperial pint, quart and gallon, US cup
TimeConverter	time	ns, µs, ms, s, min, h, d, week, year
TemperatureConverter	temperature	celsius, fahrenheit, kelvin
SpeedConverter	speed	m/s, km/h, mph, knot, ft/s
PressureConverter	pressure	Pa, kPa, bar, atm, psi, torr, mmHg, inHg
EnergyConverter	energy	J, kJ, cal, kcal, Wh, kWh, BTU, eV, ft-lbf
PowerConverter	power	W, kW, MW, hp, PS, BTU/h
AngleConverter	angle	degree, radian, gradian, turn, arcminute, arcsecond
DigitalStorageConverter	digital storage	bit, B, kB, MB, GB, KiB, MiB, GiB

The full list of units and every name they answer to is in docs/units.md. Conversions use the exact published definitions, for example 1 lb = 0.45359237 kg, 1 in = 0.0254 m and 1 US gallon = 3.785411784 L.

Customising

Add a synonym for a name that your own data uses, or add a whole unit:

var converter = new MassConverter("kg", "lbs");

converter.AddSynonym("kg", "MTOW (KG)");           // another name for an existing unit
converter.AddUnit("pallet of 250 kg", 1d / 250);   // factor: how many of the new unit make up one kilogram

converter.UnitLeft = "MTOW (KG)";
converter.UnitRight = "pallet of 250 kg";
double pallets = converter.LeftToRight(3000);      // 12

A converter is a table of factors, so defining your own is short. Each factor is how many of the unit make up one base unit:

public class MyLengthConverter : BaseUnitConverter
{
    public MyLengthConverter(string leftUnit, string rightUnit)
    {
        var units = new UnitFactors("m")           // the base unit
        {
            { new UnitFactorSynonyms("m", "metre"), 1 },
            { new UnitFactorSynonyms("furlong", "furlongs"), 1d / 201.168 },
            { "rod", 1d / 5.0292 },                // strings convert to a single-name unit
        };

        Instantiate(units, leftUnit, rightUnit);
    }
}

An unknown unit throws UnitNotSupportedException, and adding a name that already exists throws UnitAlreadyExistsException.

Notes on precision

• Values are double. Conversions divide by the source factor and multiply by the target factor, so results can differ from the exact value in the last digits.
• A result that differs from a whole number only by floating-point rounding error (such as 2.9999999999999996) is returned as that whole number. Other values are never altered.
• Temperature scales are converted with formulas, because they do not differ by a single factor.
• A year is 365 days and a leap year 366 days.

Upgrading from 1.x

Version 2.0 keeps the public API and every unit name from 1.x. It drops .NET Framework 4.0 and .NET Standard 1.3 and makes a few corrections, including the US quart, which was converted with the factor of the US pint. See the changelog for the full list.

Questions and ideas

Ask questions and suggest new units in Discussions. Use issues for wrong results and other bugs.

Contributing

Contributions are welcome, from a missing unit to a new converter. Please read the contributing guidelines and the code of conduct. To report a vulnerability, follow the security policy.

Maintainers

Maintained by @atulmish. Many thanks to the original authors, @Nick-Lucas and @gkampolis, for creating the library.

License

MIT