# Welcome to **mp-units**!

**mp-units** is a compile-time enabled feature-rich Modern C++ header-only library that provides
compile-time dimensional analysis and unit/quantity manipulation. Its key strengths include safety,
performance, and developer experience.

The library source code is hosted on [GitHub](https://github.com/mpusz/mp-units) with a permissive
[MIT license](https://github.com/mpusz/units/blob/master/LICENSE.md).

!!! important "Help needed!"

    The **mp-units** library might be the subject of ISO standardization for C++29. More on this can
    be found in the ISO C++ proposal [P1935](https://wg21.link/p1935). We are actively looking for
    parties interested in field-trialing the library.

??? info "Supported compilers"

    This library tries to provide the best user experience possible with the C++ language.
    To achieve that, it extensively uses C++20 features and the
    [explicit object parameter](https://en.cppreference.com/w/cpp/language/member_functions#Explicit_object_parameter)
    from C++23.

    Even though the library benefits from C++23 (if available), C++20 is enough to compile and
    use all of the library's functionality. C++23 features are hidden behind
    a [preprocessor macro](users_guide/framework_basics/systems_of_quantities.md#defining-quantities)
    providing a backward-compatible way to use it.

    As of today, the library compiles fine on the following compilers (or newer):

    - gcc-11
        - please note that we observed some ICEs on gcc-11
        - no problems with gcc-12.2+
    - clang-16