OK, so I tried to test it in practice, starting from 120 MB down to 25 MB. The largest that went through had 35 MB; the larger ones bounced with:

> Remote Server returned '552-5.2.3 Your message exceeded Google's message size limits. Please visit 552-5.2.3 https://support.google.com/mail/?p=MaxSizeError to view our size 552 5.2.3 guidelines.

That makes sense, because the attachment is going to be base64 encoded within the email and thus the size is inflated by 33%. This results in the size being roughly 47 MB in size.

You can easily search around that the Gmail limit for personal users is 50MiB, recently enlarged from 25 MiB. As the other poster says, even between Gmail accounts I still have trouble sending files larger than 30MiB.