A SASS Mixin (written in SCSS) for converting pixels to rems.

gistfile1.txt

// rem (Mixin)
// -----------
//
// Return font-size with a rem value based on the desired pixel value, as well
// as a fallback font-size value in em units (for IE8).
//
// Usage
//
//      h1 {
//          @include rem(font-size, 25, $fallback: false);
//      }
//
// Parameters
// 
//      $property:  (property name) The desired property to apply the $value.
//      $value:     (int, optional) The target pixel value to be achieved
//                      as rems. Defaults to $text.
//      $divisor:   (int, optional) Usually represents the root font-size
//                      but is also the unit by which `$value` is divided to
//                      calculate the final result. Typically this value is
//                      only changed if your root font-size is something other
//                      than the 16px. Defaults to 16.
//      $fallback:  (boolean, optional) Declare whether you wish the pixel
//                      versions of the $property are compiled. Defaults
//                      to False.

@mixin rem($property, $value: $text, $divisor: 16, $fallback: true) {
    @if type-of($property) == 'number' {
        @warn '$property value must be set';
    }
    #{$property}: $value * 1px;
    #{$property}: ($value / $divisor) * 1rem;
}