How to calculate a rough 'chance of admission'?
I think your chances of admission to MIT are near zero. Nothing about you, just numbers. They, and similar places, attract many many many high high high quality applicants. What you need, instead of a prediction formula is a plan to optimize your chances to get into a suitable program - one in which you will be happy and can be reasonably assured of success. 

To do this you need a list of reasonable schools that is a little broader than you think your CV and letters from professors will support. Choose some schools a bit more "elite" than you think you would be assured of entry, more in the "mid range" of your expectations, and a few that might not be quite so prestigious. Try not to over or underestimate your potential - get whatever feedback you can from your current professors on that. Perhaps they have a sense of what has happened to students similar to you from their past. 

Since you have a year, yet, you can work with a smaller selection of your list, including your top choice. Apply to those first to see what happens. Whenever possible, try to get personal feedback on your application by speaking to people who can affect your acceptance. This might be professors, department heads, admissions officers. They probably won't give you all the information you want to have, but it might be enough to judge whether you are being seriously considered or not. Don't be passive in contacting people if they make that option available, but don't be a pest. 

If your first batch seems to need supplementing, you have more for the second round. If it seems like people are taking too long to reply, send out a few more applications. 

If you get an offer that is not a high choice for yourself, and if you have time yet, you could try a few more schools that you would find more desirable. Use any offer as a backup rather than immediately accepting it if that is possible. As you get any feedback, and if your situation allows, discuss the results with a faculty member at your current school. 

But unless you are the reincarnation of Einstein, don't apply in top-down order from your list. And note that even Einstein got rejection letters. Nothing is certain. You have a lot of competition. Any formula is just probabilistic in any case. Follow a plan.