Solution taken from Converting Your Typographic Units with Sass:
@function convert($value, $currentUnit, $convertUnit){
   @if $currentUnit == px{
      @if $convertUnit == ems{
        @return $value / 16 + 0em;
      }
      @else if $convertUnit == percent{
        @return percentage($value / 16);
      }
   }@else if $currentUnit == ems{
      @if $convertUnit == px{
        @return $value * 16 + 0px;
      }
      @else if $convertUnit == percent{
        @return percentage($value);
      }
   }@else if $currentUnit == percent{
      @if $convertUnit == px{
        @return $value * 16 / 100 + 0px;
      }
      @else if $convertUnit == ems{
        @return $value / 100 + 0em;
      }
   }@else if $currentUnit == pts{
      @if $convertUnit == px{
        @return $value * 1.3333 +0px;
      }
      @else if $convertUnit == ems{
        @return $value / 12 + 0em;
      }
      @else if $convertUnit == percent{
        @return percentage($value / 12)
      }
   }
}
							
							
						 
Related: http://answall.com/questions/27133
– Woss
Dude, take a look at this: https://www.sitepoint.com/converting-typographic-units-sass/ might help you, there’s a function there that does this conversion, compared to the pattern I find difficult because each font has its own dimensions.
– Mathiasfc