How to attach a large file in gmail?

Right then. Gmail has a 25MB limit for direct attachments. For anything larger, it cleverly uses Google Drive.

Simply try to attach your file as you normally would. Gmail will automatically detect the large size. It then uploads the file to your Google Drive for you. A link to the file is placed in your email instead. The recipient just clicks this link to access it. It’s a rather seamless process, really.