Category:Spell Cost

A spell's Magicka cost is the sum of the costs of each of the effects in the spell. The cost of each effect is determined by several parameters: which effect (specifically the Effect's Base Cost), and its Magnitude, Duration, Area, and Range (specifically, whether or not the spell is on Target). The actual cost to cast the spell is also affected the caster's skill in the spell's school and Luck stat. The effect of each of these depends on several game settings:

Each individual effect in a spell contributes to the final cost of the spell independently. The contributions from a single effect follow this formula:

 Effect Factor = Base Cost * fMagicDurMagBaseCostMult
 Magnitude Factor = Magnitude ^ fMagicCostScale
 Duration Factor = Duration (minimum of 1)
 Area Factor = Area * fMagicAreaBaseCostMult (minimum of 1)
 Range Factor = if Target, fMagicRangeTargetCostMult; else, 1
 Skill Factor = 
   fMagicCasterSkillCostBase + fMagicCasterSkillCostMult * (1 - Effective Skill/100)

 Unscaled Effect Cost = Effect Factor * Magnitude Factor * 
     Duration Factor * Area Factor * Range Factor (minimum 1)
 Scaled Effect Cost = Effect Factor * Magnitude Factor * 
     Duration Factor * Area Factor * Range Factor * Skill Factor (minimum 1)

Unscaled Effect Cost and Scaled Effect Cost are both rounded down. All other quantities above are not rounded.

The overall cost of the spell ends up being:

 Unscaled Spell Cost: sum of all the Unscaled Effect Costs
 Scaled Spell Cost: sum of all the Scaled Effect Costs

The Scaled Spell Cost is the amount of magicka it takes to cast the spell. It is the quantity listed next to the spell in-game in your magic menu.

The Unscaled Spell Cost is the value listed in the Construction Set as "spell cost". It determines what mastery level the spell is, and thus the minimum skill level required to cast the spell, but has no other effect. The Mastery level is determined by comparing the Unscaled Spell Cost to the relevant game settings:

The above applies to auto-calculated spells only. Spells made in the spellmaker are considered auto-calculated, as are those flagged as auto-calculated in the Construction Set. If the spell is not auto-calculated, a simpler formula is used:

 Unscaled Spell Cost = the value manually specified in the Construction Set
 Scaled Spell Cost = Unscaled Spell Cost * Skill Factor (rounded down) (no minimum)

Note

• An auto-calculated spell's school is determined by the most expensive single effect, not by which school has the most combined cost, so multiple effects from a single school will not help that school "win".
• The formulas above for auto-calculated scaled spell cost and unscaled spell cost are those used in the game. However, the Construction set itself calculates values by a slightly different formula, causing minor discrepancies between the costs and mastery levels of spells in the game and in the CS. The only difference is, the CS does not raise Unscaled Effect Cost or Scaled Effect Cost to a minimum of 1. Thus, in the CS an auto-calculated spell may be shown as having a (scaled or unscaled) cost less than the number of effects, but in the game that is impossible.
• Enchantment cost (in Charge) uses the exact same formula, but is not affected by Luck or any skill.
• The cost in Septims to buy any spell is equal to three times its Magicka cost. (the exact multiplier is determined by a Game Setting, probably fSpellmakingGoldMult, but this is currently untested).