You have 3 jump-ranges for your ship (4 actually) - laden, unladen, max, and current.
Laden, Unladen, and Current are obvious, I hope. The first two assume a full fuel-tank, although I'm not sure if they take extra fuel-tanks into account (I've never used one). The latter is what your ship can currently do with current fuel-levels and cargo.
Max is for when you jump with minimum fuel onboard. For example, my AspX for DWE1 "only" had 32.6 LY range. For one of the final jumps to Beagle Point I needed 33.4LY range. Instead of using Jumponium, I just jumped with a half-empty tank which gave me the extra bit of range I needed.
This is a "trick" when exploring sparse regions of space - instead of fuelling up fully, you only fuel up enough to make the next jump. This can give you quite a bit of extra range, making the difference between being able to make the jump or not. Of course, if the destination system is not scoopable, you're stuffed, so this type of exploration requires a lot of patience and care. I find it very rewarding though.