Last week we mentioned that you can search Gmail based on message size, which is great for finding attachments that take up too much space in your inbox. Gmail just boosted those features to make size searches easier and more specific.
Previously, you had to search in bytes, which isn't terribly helpful if you are looking for a 50MB file. Instead of typing size:50000000, you can now just type size:50m. Additionally, if you're looking for old messages you can now use the older_than search modifier. For example, olderthan:1y will display any messages that are more than a year old.
Search for emails by size and more in Gmail [Official Gmail Blog]