Google gives us a lot of space in Gmail to store our emails and their attachments. However you may run out of space. In that case you can easily free some space by deleting emails with large attachments. How can you find them?
Searching by size is very simple. You just type size: and then the minimum number of the bytes you want to search for. For example, you'd type size:1000000 for messages greater than 1MB.
Here are some links ready for you:
Search for attachments greater than 5MB (size:5000000)Search for attachments greater than 10MB (size:10000000)Search for attachments greater than 25MB (size:25000000)
Update: Google has introduced an easier way to search for large attachments or old e-mails. Now you can type the size in MB like this size:5m. Additionally if you want to search for e-mails older that 1 year you can type older_than:1y