Want to figure out what is taking up all your space in Gmail? It’s easy — just use the size operator in the search box. You can combine it with the has:attachment operator to make sure that you’re just filtering for attachments, but it will work either way.
Use a search like this to return all emails larger than 10 MB:
You can also use regular numbers, like size:10000000 for the number of bytes if you want to get even more crazy. But it’s much simpler to use the 10mb operator. Or 5mb. Or whatever.