Senior Member. “So far” means to this point in time. For example, “So far, no one has been able to reach the top”. “By far” means “much more” as in “John is by far the best student in the class”.

Is it by far or so far?

By far modifies comparatives and superlatives, and indicates that the degree to which they exceed other compared things is very, very great. This is the best one by far. So far is a distance measurement meaning as far as this. It's often used with the TIME is DISTANCE metaphor theme to mean up until now.

What does it mean by by far?

phrase. You use the expression by far when you are comparing something or someone with others of the same kind, in order to emphasize how great the difference is between them. For example, you can say that something is by far the best or the best by far to indicate that it is definitely the best.