To increase icon sizes relative to their container, use the fa-lg (33% increase), fa-2x, fa-3x, fa-4x, or fa-5x classes.
<i class="fa fa-camera-retro fa-lg"></i> fa-lg
<i class="fa fa-camera-retro fa-2x"></i> fa-2x
<i class="fa fa-camera-retro fa-3x"></i> fa-3x
<i class="fa fa-camera-retro fa-4x"></i> fa-4x
<i class="fa fa-camera-retro fa-5x"></i> fa-5x
Use fa-fw to set icons at a fixed width. Great to use when different icon widths throw off alignment. Especially useful in things like nav lists & list groups.
<div class="list-group">
<a class="list-group-item" href="#"><i class="fa fa-home fa-fw" aria-hidden="true"></i> Home</a>
<a class="list-group-item" href="#"><i class="fa fa-book fa-fw" aria-hidden="true"></i> Library</a>
<a class="list-group-item" href="#"><i class="fa fa-pencil fa-fw" aria-hidden="true"></i> Applications</a>
<a class="list-group-item" href="#"><i class="fa fa-cog fa-fw" aria-hidden="true"></i> Settings</a>
</div>