Units.NET

Everyone have written their share of trivial conversions - or less obvious ones where you need to Google that magic constant.

Stop littering your code with unnecessary calculations. Units.NET gives you all the common units of measurement and the conversions between them. It is light-weight, unit tested and supports PCL.

Installing

Run the following command in the Package Manager Console or go to the NuGet site for the complete relase history.

Build Targets:

Portable 4.0 Profile328 (.NET 4, Silverlight 5, Win8, WinPhone8.1 + WP Silverlight 8)
Portable 4.5 Profile259 (.NET 4.5, Win8, WinPhone 8.1 + WP Silverlight 8)
.NET 3.5 Client
.NET 4.5.1

Features

28 units of measurement
Generated code for uniform implementations and fewer bugs
Immutable structs implementing IEquatable, IComparable and operator overloads
Parse unit abbreviations in multiple cultures
ToString() variants for custom cultures and format patterns
Extensible with custom units
Serializable with JSON.NET
Over 500 unit tests to ensure conversions and localizations are in order

Static Typing

// Convert to the unit of choice - when you need it
Mass weight = GetPersonWeight();
Console.WriteLine("You weigh {0:0.#} kg.", weight.Kilograms);

// Avoid confusing conversions, such as between weight (force) and mass
double weightNewtons = weight.Newtons; // No such thing

// Some popular conversions
Length meter = Length.FromMeters(1);
double cm = meter.Centimeters; // 100
double yards = meter.Yards; // 1.09361
double feet = meter.Feet; // 3.28084
double inches = meter.Inches; // 39.3701

Unit Enumeration

All units have a corresponding unit enum value. This is useful when selecting the unit representation at runtime, such as presenting a choice of units to the user.

/// <summary>Convert the previous height to the new unit.</summary>
void OnUserChangedHeightUnit(LengthUnit prevUnit, double prevValue, LengthUnit newUnit)
{
    // Construct from dynamic unit and value
    var prevHeight = Length.From(prevValue, prevUnit);

    // Convert to the new unit
    double newHeightValue = prevHeight.As(newUnit);

    // Update UI with the converted value and the newly selected unit
    UpdateHeightUI(newHeightValue, newUnit);
}

Culture and Localization

The culture for abbreviations defaults to Thread.CurrentUICulture and falls back to US English if not defined. Thread.CurrentCulture affects number formatting unless a custom culture is specified. The relevant methods are:

ToString()
GetAbbreviation()
Parse/TryParse()
ParseUnit/TryParseUnit()

var usEnglish = new CultureInfo("en-US");
var russian = new CultureInfo("ru-RU");
var oneKg = Mass.FromKilograms(1);

// ToString() with Thread.CurrentUICulture as US English and Russian respectively
"1 kg" == oneKg.ToString();
"1 кг" == oneKg.ToString();

// ToString() with specific culture and string format pattern
"mg 1.00" == oneKg.ToString(MassUnit.Milligram, usEnglish, "{1} {0:0.00}");
"мг 1,00" == oneKg.ToString(MassUnit.Milligram, russian, "{1} {0:0.00}");

// Parse measurement from string
Mass kg = Mass.Parse(usEnglish, "1.0 kg");
Mass kg = Mass.Parse(russian, "1,0 кг");

// Parse unit from string, a unit can have multiple abbreviations
RotationalSpeedUnit.RevolutionPerMinute == RotationalSpeed.ParseUnit("rpm");
RotationalSpeedUnit.RevolutionPerMinute == RotationalSpeed.ParseUnit("r/min");

// Get default abbreviation for a unit
"kg" == Mass.GetAbbreviation(MassUnit.Kilogram);

Helper Construction Methods

Construct measurements with various helper methods for convenience and readability.

Force.FromPressureByArea(Pressure p, Length2d area)
Force.FromMassAcceleration(Mass mass, double metersPerSecondSquared)

Precision and Accuracy

A base unit is chosen for each unit class, represented by a double value (64-bit), and all conversions go via this unit. This means there will always be a small error in both representing other units than the base unit as well as converting between units.

Units.NET was intended for convenience and ease of use, not highly accurate conversions, but I am open to suggestions for improvements.

The tests accept an error up to 1E-5 for most units added so far. Exceptions include units like Teaspoon, where the base unit cubic meter is a lot bigger. In many usecases this is sufficient, but for others this may be a showstopper and something you need to be aware of.

For more details, see Precision.

Serialization

UnitsNet.Serialization.JsonNet (nuget, src, tests) for JSON.NET

Important! We cannot guarantee backwards compatibility, although we will strive to do that on a "best effort" basis and bumping the major nuget version when a change is necessary.

The base unit of any unit should be be treated as volatile as we have changed this several times in the history of this library already. Either to reduce precision errors of common units or to simplify code generation. An example is Mass, where the base unit was first Kilogram as this is the SI unit of mass, but in order to use powershell scripts to generate milligrams, nanograms etc. it was easier to choose Gram as the base unit of Mass.

What It Is Not

It is not an equation solver
It does not figure out the units after a calculation

Want To Contribute?

This project is still early and many units and conversions are not yet covered. If you are missing something, please help by contributing or ask for it by creating an issue.

Please read the wiki on Adding a New Unit.

Generally adding a unit involves adding or modifying UnitsNet\Scripts\UnitDefinitions\*.json files and running UnitsNet\Scripts\GenerateUnits.bat to regenerate the source code and test code stubs, then manually implementing the new unit conversion constants in the test code.

Fork the repo
Do work on branches such as feature/add-myunit and fix/34
Create a pull request

Continuous Integration

A TeamCity build server performs the following:

Build and test pull requests. Notifies on success or error.
Build and test master branch.

Contact me if you have any questions.

BoGrevyDynatest/UnitsNet