How do you convert bifocal eyeglass prescription to reading eyeglass prescription?

It is not that easy. Some people believe that a simple set of numbers for a prescription can be plugged into a formula and somehow a new prescription will be generated.

It is best to go to your local Optometrist and fully explain what kind of reading do you want to perform best. Ther will be a certain amount of positive (convex) lens power that will provide the needed amount of correction at the most comfortable distance for the size of document or book you read most. An approximate result that can give you an idea is to go to a Walgreens or similar type of Pharmacy and try different powers reading eyeglasses; but for best results a good Optometrist is best.