Quickly Calculating Spells Per Day

By Pleiades LLC

pleiad@hotmail.com

Copyright 2002

Introduction

For several months now I�ve found times where I wanted to be able to figure a Wizard or Cleric�s Spell Per Day without having to refer to the PHB every time. This being a minor inconvenience in my daily life of D&D and being lazy to boot I managed to procrastinate about it for several months. Well, I finally had a little time on hands and was reading through the DMG when I noticed a line that mentioned a rule of thumb for Spells. It got me going since I haven�t seen it posted anywhere and thought I�d share the results.

I adopted the approach of wanting to know at what level a character would get their next Spell Slot (increase in Spells Per Day) for a particular Spells Level. This is a nice little bit of information to know and learning its general rule helps in quickly figuring the Spells Per Day chart. The former is nice to know when playing a character and the later is nice to know as a DM when creating NPCs. As it turns out it is pretty simple calculation to do.

Cavet: for one or two of the classes this technique breaks down for 19th and 20th spellcasters who are casting 9th level spells. It looks like this is due to some rounding on the Spell casting chart. Apparently, WotC thought it was important that 20th level Wizards be able to cast four 9th level spells and I�m not going to argue with the wisdom of that decision. Besides I was lazy (too lazy to go and look it up in the PHB in the first place) and didn�t want to overly complicate things.

I do know that the following works well for 1-8th level spells and most of the 9th level spells. So if you can remember what the Spell Per Day chart looks like for 9th level spells then this will work for you.

The Next Spell Slot

Clerics and Wizards get their next Spell Slot at a particular level according to this method:

     Level(n) = Spell Level * 2 + (n-1)(n)/2 � 1, 
     where n is the Spell Slot increment.

Example: If we are considering a 17th level Wizard who is wondering when they will get their next 8th level spell. The value for n = 3 since a 17th level Wizard already has two 8th level spell slots. It works out as follows:

     Level(3) = 8 * 2 + (3-1)(3)/2 � 1 = 18

See a Wizard would get their third 8th level spell slot at level 18. Wizards and Sorcerers each have four Spell Slot increases and Clerics have five.

Note that the Spell Slot increment isn�t the same as the Spells per Day. A Wizards Spell Slot increment does work out to be their Spells Per Day. This is mostly true for Clerics as well but they also get one domain spell for each Spell Level. Sorcerers just receive a few extra spells so their Spells Per Day is higher. To make this calculation for Sorcerers one would have to subtract two from a particular entry on the Spells Per Day chart to find a particular increment.

Example: A 10th level Sorcerer has five 4th level spells; however, it is only their 3rd (5-2=3) increase in Spell Slots for 4th level spells.

Sorcerers, also, use a slightly different chart for calculating their Spells Per Day so the following method should be used:

     Level(n) = Spell Level * 2 + n - 1, 
     where n is the Spell Slot increment.

Example: A 5th level Sorcerer is wondering when they get their first 3rd level spell. Sorcerers only get four Spell Slot increases but have a higher number of minimum Spells Per Day. We have to adjust the Spells Per Day by 2 to find the Spell Slot increment so 3-2= 1. The calculation works out as:

     Level(n) = 3 * 2 + 1 -1 = 6

Quickly Calculating Spells Per Day

Doing a little inspection allows us do make some simplifications that enable us to quickly figure out how many spells a particular caster has. Looking at the term (n-1)(n)/2 � 1 from the Next Spell Slot formula for Clerics and Wizards we see that we can evaluate it for n = 1, 2, 3, 4, and 5 yields { -1, 0, 2, 5, 9 }.

Considering a Wizard we see that if we evaluate:

     Level(n) >= Spell Level * 2 and { -1, 0, 2, 5, 9 }

we can calculate the Spells Per Day for an arbitrary class level.

Example: How many 4th level spells does an 11th level Wizard receive? Looking at

     11 >= 4 * 2 and { -1, 0, 2, 5, 9 }

Moving down the array counting the elements that satisfy it will give us the number of Spells Per Day. We can see that { 8-1, 8+0, 8+2 } are all less than or equal to 11 so the Wizard has three 4th Level Spells Per Day. Personally, I tend to look for the element that invalidates it and use the index of the one to its left. In this case 8+5 > 11 so the 3rd item in the list is the value for Spells per Day.

If we were considering a Cleric then we would just need to add 1 to the result to account for the additional domain spell. If we were considering a Sorcerer then we would need to add 2 to the result to account for the additional spells that Sorcerers cast. Sorcerers would also require us to evaluate a different term. For Sorcerers the term n-1 yields { 0, 1, 2, 3 } for n = 1, 2, 3, and 4 for four Spell Slot increases.

Summary

• Level(n) = Spell Level * 2
• Wizards & Clerics { -1, 0, 2, 5, 9 }
• Sorcerers { 0, 1, 2, 3 }
• Wizards, Clerics, and Sorcerers (or 0, 1, 2)

and some quick calculations allow for quick recall of some of the PHB tables for Clerics, Sorcerers, and Wizards.

Copyright © 2001-2002 Pleiades LLC. All rights reserved.