Theme Customizing: Site Icon & Logo
One of the first steps you will take when setting up your site is adding your own site icon and logo. It's easy to upload your icon and logo from the Theme Customizer: Appearance -> Customize -> Icon & Logo.
Site Icon. The Site Icon (also known as favicon) is used as a browser and app icon for your site. Icons must be square, and at least 512px wide and tall.
Logo Type. You can keep not only to use the default text logo but also to upload your own custom image logo and retina image logo if needed.
Regular Logo. The Regular Logo image's maximum height must be 100px.
Retina Logo. The Retina Logo is displayed on devices that have a higher than normal pixel density. Using this option will ensure that your logo looks great on all devices (e.g., iPad with retina display). The Retina Logo should be uploaded at exactly double the dimensions of your regular logo. So if your regular logo is 200x100 then your retina logo would be 400x200.