Generated by SassMeister.com.

SassMeister-input.scss

// ----
// libsass (v3.2.5)
// ----

//

@function strip-units($number) {
  @return $number / ($number * 0 + 1);
}

// convert-units function
// by Dariusz Sikorski http://prettyminimal.com
//                     http://www.dariuszsikorski.pl
// convert any css font-size unit, to other unit
// usage: convert-units( inputValue, outputUnit)
// example: convert-units(32px, rem);

@function convert-units(
  $value,
  $outputUnit: px
){
  // default unit sizes measured in px for 1920x1200 (imac 24') screen
  // http://www.w3schools.com/browsers/browsers_display.asp
  // http://www.w3schools.com/cssref/css_units.asp
  $units: (
    px:   1,
    em:   16,
    ex:   9.12656,
    ch:   9.78827,
    rem:  16,
    vw:   17.4545,
    vh:   9.86364,
    vmin: 9.86364,
    vmax: 17.4545,
    %:    0.16,
    cm:   37.7953,
    mm:   3.77953,
    in:   96,
    pt:   1.33333,
    pc:   16
  );
  
  // check if input value is a number
  @if type-of($value) == number {
    $inputUnit: unit($value);
    
    // define variable for value to px conversion
    $pxValue: 1;
    
    // define variable for px to output value conversion
    $outputValue: 1px;
    
    // if input value was unitless, convert it to pixels
    @if unitless($value){
      $value: $value * 1px;
    }
    
    // convert input value to px units
    // @each Key, Value in Map
    @each $keyUnit, $size in $units {
      @if $inputUnit == $keyUnit {
        $pxValue: strip-units($value) * $size;
      }
    }
    
    // convert pxValue to output value
    @each $keyUnit, $size in $units {
      @if $outputUnit == $keyUnit {
        // $outputValue: $pxValue;
        // $outputValue: $size;
        // $outputValue: $outputUnit;
        $outputValue: length($pxValue / $size,  $outputUnit);
      }
    }

    @return $outputValue; 
  }
  
  // return communicate when $value is not a number
  @return "value must be a number";
}

@function length($number, $unit) {
  $strings: 'px' 'cm' 'mm' '%' 'ch' 'pica' 'in' 'em' 'rem' 'pt' 'pc' 'ex' 'vw' 'vh' 'vmin' 'vmax';
  $units:   1px  1cm  1mm  1%  1ch  1pica  1in  1em  1rem  1pt  1pc  1ex  1vw  1vh  1vmin  1vmax;
  $index: index($strings, $unit);

  @if not $index {
    @warn "Unknown unit `#{$unit}`.";
    @return false;
  }

  @return $number * nth($units, $index);
}


.test {
  $height: 50px;
  
  height: $height;
  converted: convert-units($height, rem);
  stripped: strip-units($height);
  
  manualConvert: convert-units(50px, rem);
  manualStrip: strip-units(3.125rem);
  
  pipe: strip-units( convert-units($height, rem) );
}

SassMeister-output.css

.test {
  height: 50px;
  converted: 3.125rem;
  stripped: 50;
  manualConvert: 3.125rem;
  manualStrip: 3.125;
  pipe: 3.125;
}