Sometimes I find that I need to reference some minor factiod about the 3.5 ruleset. Here are some links dealing with this.
If you need to get a rough idea on how much XP a party will get from an average encounter for a certain level, consider the Encounter Calculator v3.5.
http://www.geocities.com/edymnionii/EPLvsEL.html
It's a great way to figure out how many encounters a party might need. Remember to divide by 10 (assuming your experience slider for the module is set to 10%).
Credits: Tiera Starr, John Dells, arcady, Maladaar.
Thanks to dirtywick for pointing this out.
I know I forget this every few months, so here it is thanks to kevinodie and Jassper who posted this on the official forums:
(Current Level * NextLevel)*500 = XP needed for next level.
So level 1 = 0xp,
(level 1 * Level 2)*500 = (1*2)=2*500= 1000 xp for level 2
(level 2 * Level 3)*500 = (2*3)=6*500= 3000 xp for level 3
ect.
This can also be expressed:
N*(N-1)*500 is the minimum XP needed to get to Nth level.
Originally posted here:
http://nwn.bioware.com/forums/viewtopic.html?topic=470745&forum=46