Save DC?

[Sir Yvain]

Does anyone know how to determine a spell DC?

I always see spells like Fear and it says the target is entitled to a Will Save

Or

Many Fire effects entitle the target to a Reflex save.

I don't know how to Figure out the DC though. I've seen specific abilities that tell you explicitly what the DC is, but I don't know how to figure out general DC's. Can anyone help here?

[Eldariel]

3.5? 10 + Spell Level + Ability Modifier. And Supernatural Ability DCs and such are 10 + ½ HD + Ability Modifier.

[Sir Yvain]

Yes it is 3.5

Thanks very much

[KillianHawkeye]

Note: for spells, you use the ability modifier of whatever ability score your spellcasting is based on (Int for Wizards, Wis for Clerics/Druids, Cha for Bards/Sorcerers, etc.). Although I think there is a class or two that uses one ability score for bonus spells/highest spell level and a different score for save DCs, but those are pretty rare.