Just as a math puzzle, I want to see whether it's possible to deduce the formula that converts XP points to levels... You can find out your target XP by mousing over the blue thermometer next to your level, at the top left of every page (incl. this one), it's the second number (the one after the slash).
I'm level 27 and I need a total of 22,823 XP to get to the next level.