What is the volume of a Fireball?

[LostSoul]

Yep, just as the title asks. Does a fireball expand into squares above or below?

Fireball
Evocation [Fire]
Level: Sor/Wiz 3
Components: V, S, M
Casting Time: 1 standard action
Range: Long (400 ft. + 40 ft./level)
Area: 20-ft.-radius spread
Duration: Instantaneous
Saving Throw: Reflex half
Spell Resistance: Yes

Spread: Some effects, notably clouds and fogs, spread out from a point of origin, which must be a grid intersection. The effect can extend around corners and into areas that you can’t see. Figure distance by actual distance traveled, taking into account turns the spell effect takes. When determining distance for spread effects, count around walls, not through them. As with movement, do not trace diagonals across corners. You must designate the point of origin for such an effect, but you need not have line of effect (see below) to all portions of the effect.

 

[Thanee]

Of course. It's a fireball not a firecircle.

Bye
Thanee

 

[hafrogman]

Roughly 33,510 cubic feet

 

[Iuz]

The volume of a sphere can be found by the formula:
volume=4/3¶r3


(four thirds pi radius cubed)

 

[BSF]

Heh - I remember playing with fireball volume in previous editions. A friendly reminder that spread will fill it's radius, if it can. But you cannot cast a fireball into a 10' x 10' x 335' of corridor and expect it to fill the corridor.

Of course, if you want to house-rule that, go ahead.

 

[The Souljourner]

Ahh.... remember 2nd edition, when that worked? Good times, good times.

Now, it just fills up the radius, even going around corners. Won't go outside the radius, however.

-The Souljourner

 

[andargor]

If you want to get technical per the RAW, the volume is exactly 23,000 cu. ft.

Here's a hemisphere, using the diagonals rule:

   oo
 oooooo
 oooooo
oooooooo
oooooooo 44 x 5' cubes = 5500 cu. ft. 
 oooooo
 oooooo
   oo


     
  oooo 
 oooooo
 oooooo 
 oooooo  32 x 5' cubes = 4000 cu. ft.
 oooooo
  oooo 
     

     
       
   oo  
  oooo  
  oooo   12 x 5' cubes = 1500 cu. ft.
   oo 
       
     

     
       
       
   oo 
   oo    4 x 5' cubes = 500 cu. ft.

Multiply that by 2 and you get 23,000 cu. ft.

Rounding out those diagonals really makes you lose volume. I'll have to lodge a complaint with Wizards...

Andargor

 

[Pielorinho]

Some people think that with heighten spell, the volume goes all the way up to 11.

Daniel

 

[MerakSpielman]

Multiply that by 2 and you get 23,000 cu. ft.

Rounding out those diagonals really makes you lose volume. I'll have to lodge a complaint with Wizards...

Andargor

I don't think you'd multiply the first diagram by two... or maybe you would.

 

[andargor]

I don't think you'd multiply the first diagram by two... or maybe you would.

Since you calculate the radius from a grid intersection, the midpoint is "below" the first one. So there's another mirroring it below.

Andargor