Font-Awesome/less/sizes.less

// icon sizes
// --------------------------

// scale icon size by n
.createIconScales(@iterator: 1) when(@iterator <= length(@fa-var-scales)) {
  @fa-icon-scale-name: extract(extract(@fa-var-scales, @iterator), 1);
  @fa-icon-scale-name-unquoted: ~"@{fa-icon-scale-name}";
  @fa-icon-scale: extract(extract(@fa-var-scales, @iterator), 2);

  .@{fa-css-prefix}-@{fa-icon-scale-name-unquoted} {
    font-size: unit(@fa-icon-scale, em);
    line-height: unit(@fa-icon-scale * 0.75, em);
    vertical-align: -15%;
  }
  .createIconScales((@iterator + 1));
}
.createIconScales();

// multiply icon size by n
.createIconMultipliers(@iterator: 1) when(@iterator <= length(@fa-var-multipliers)) {
  @fa-icon-multiplier-name: extract(extract(@fa-var-multipliers, @iterator), 1);
  @fa-icon-multiplier-name-unquoted: ~"@{fa-icon-multiplier-name}";
  @fa-icon-multiplier: extract(extract(@fa-var-multipliers, @iterator), 2);

  .@{fa-css-prefix}-@{fa-icon-multiplier-name-unquoted} {
    font-size: unit(@fa-icon-multiplier, em);
  }
  .createIconMultipliers((@iterator + 1));
}
.createIconMultipliers();