Pixel to EM

pxtoem.scss

// Enter a base pixel size in px (without the px)
$basepx: 16;

// Convert PX to EM global function
@function pxtoem($px, $basepx){
    @return ($px/$basepx)+0em;
}

//Then on a class or element you can use:
h1 { font-size: pxtoem(36, $basepx); }
h2  { font-size: pxtoem(28, $basepx); }
h3  { font-size: pxtoem(22, $basepx); }
.class { font-size: pxtoem(14, $basepx); }

//or on your media queries:
@media all and (min-width: pxtoem(600, $basepx)) {
    .class {}
}