Thanks to a recent Gmail search update, it is now easier than ever before to search for messages by size and date. For example, you can now search for larger:5m to yield all messages that have attachments larger than 5MB. Better yet, you can combine this with the older_than operator and search for size:5m older_than:1y, thus yielding a list of all messages older than a year and larger than 5MB.
Gmail’s free space quota has always been generous, and currently stands at over 10GB (and famously, it is constantly growing, as you can see on the Gmail.com page when you’re not signed in to any account). Still, if you’ve been using a free Gmail account for years, you may have ancient photos, videos, and other large attachments clogging up your inbox and taking up precious space. Thanks to these new operators, you can now download these attachments and delete the messages that contained them, freeing up valuable space.
For a full list of Gmail’s search operators, you can check out the Gmail documentation. The operators are numerous and powerful, letting you search within particular message labels, search only for messages sent to one of your addresses (if you have several), and even search only within Google Chat messages (which are recorded on Gmail by default). Finding the message you need on Gmail has never been easier.
Source: Official Gmail Blog