I get a lot of questions about these 2 confusing words.
Em’s Simple Trick:
If you can measure it, it’s farther.
Ex: He ran his hand farther down her spine onto her butt.
why: You could measure the distance in inches or centimeters or even in hand-lengths.
How to remember: Farther has FAR in it.
FURTHER is figurative.
Ex: Complaining further will result in me pulling the car over and smacking you with my flip-flop.
Sometimes these tips don’t work. For instance: I’m further on my crocheting than you are. (I don’t crochet).
Bottom line: Farther for distance that can be measured. Further if you’re being figurative. If you don’t know, such as in the crocheting sentence above, go with FURTHER.