Which sizes do you need?
For a website favicon, 16 and 32 px cover browser tabs, bookmarks and the address bar; adding 48 px helps Windows taskbar pins. For a Windows application or shortcut icon, include 16, 32, 48 and 256 px so Explorer can pick the right one at every zoom level. Modern browsers also accept PNG or SVG favicons, but an .ico at /favicon.ico remains the most universally supported fallback.
Small sizes are unforgiving: fine detail and thin text disappear at 16 px. Pick the frame with the boldest, simplest silhouette — scrub through with the frame slider — or crop to the most recognisable part first.
Animated cursors and other icon formats
ICO files can’t animate. If you need an animated Windows cursor, the format is .ani — and ANI to GIF converts those back into GIFs. For a lossless still of any frame without icon packaging, use GIF to PNG.