Calculate sizes in EMs easily by converting from other units

em-font-size.less

@BASE_FONT_SIZE : 16px;

// translate units by parent element ratio
.emsize(@property, @desired, @base : @BASE_FONT_SIZE) {
	@{property}: 1em * (unit(@desired) / unit(@base));
}

// a wrapper for setting font size
.emfz(@desired, @base : @BASE_FONT_SIZE) {
	.emsize(font-size, @desired, @base);
}

// another helper which can be used inline. eg- padding: 0 ~`@{toem}(20, 16)`;
@toem: ~`fn = function(a, b) { return (parseFloat(a) / parseFloat(b)) + 'em'; }`;

em-font-size.scss

$BASE_FONT_SIZE : 16px;

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

// translate units by parent element ratio
@function emsize($desired, $base : $BASE_FONT_SIZE) {
	@return 1em * (strip-units($desired) / strip-units($base));
}

// a wrapper for setting font size
@mixin emfz($desired, $base : $BASE_FONT_SIZE) {
	font-size: emsize($desired, $base);
}