Favicon size

<!-- For all browsers -->
<link rel="icon" type="image/png" sizes="32x32" href="favicon-32x32.png">
<link rel="icon" type="image/png" sizes="16x16" href="favicon-16x16.png">

<!-- For Google and Android -->
<link rel="icon" type="image/png" sizes="48x48" href="favicon-48x48.png">
<link rel="icon" type="image/png" sizes="192x192" href="favicon-192x192.png">

<!-- For iPad -->
<link rel="apple-touch-icon" type="image/png" sizes="167x167" href="favicon-167x167.png">
<!-- For iPhone -->
<link rel="apple-touch-icon" type="image/png" sizes="180x180" href="favicon-180x180.png">

Source