The modern solution to multi-image favicon creation giving your website the very best SERPs page appearance.
In their Google Search Central article "Define a favicon to show in search results" Google states:
Your favicon must be a multiple of 48px square, for example: 48x48px, 96x96px, 144x144px and so on.
This is interesting as most SEO information sources suggest 16 or 32px square. Further, online SEO checkup tools often flag the Google compliant icon as an error. Clearly these tools and sources need updating. Call in the SEO renovators!
But using an icon produced by SEO Icons will make Google Search happy with your sites.
In my opinion it is wise to follow all of Google's SEO suggestions - they exist to help you and to make it easier for Google to list your site.
Using icons produced here could give your site the edge over competitors - the service is free and unlimited.
So drag your PNGs into the Convert box and get started.
If you prefer traditionally sized icons, please visit png2ico - the original tool from 2014 for producing icon files.