How deep glasses do I need if my eyesight is 40/20?

Question

i want to know an approximate glasses prescription for an eyesight of 40/20. thanks!

Answer 1

40/20 doesn't make any sense, you must mean 20/40

An approximation, assuming there is no astigmatism or other problems with the eye, and that the problem is simple myopia ( nearsighted ) it would most likely be a  -0.75  to bring the vision back to 20/20

It is a mild correction, but would make a big difference for driving, movies , classroom,  ect.