How am I gonna give you exact price savings, when on $18 amount of work you can do it is variable, while $100 on API only goes a limited amount. You can exhaust $100 on API in one work day easily. On $18 plan the limit resets daily or 12hrs, so you can keep coming back. If API pricing is correct, which it looks like because all top models have similar costs, then it is to believe that monthly plans are subsidised.

And if inference is so profitable why is OpenAI losing 100B a year