battle-mapd20-modernmap-making
I am making a map for a modern day game my DM is running, and I have an architectural image of a floor plan with listed square footage.
For a D20 Modern's 5ft grid, how would I figure out how many squares fit in an area to make it realistic? For instance, I have an area of 241 sq.ft. So how many squares would I fit in there and how would I find this information for other sq.ft.? I'm using GIMP to make the grid, if it matters. Would I just divide the 241 into 5 to find my area?
You can extrapolate from these spell area diagrams and the rules for determining the exact radius in squares.
Regardless of the shape of the area, you select the point where the spell originates, but otherwise you don't control which creatures or objects the spell affects. The point of origin of a spell is always a grid intersection. When determining whether a given creature is within the area of a spell, count out the distance from the point of origin in squares just as you do when moving a character or when determining the range for a ranged attack. The only difference is that instead of counting from the center of one square to the center of the next, you count from intersection to intersection.
You can count diagonally across a square, but remember that every second diagonal counts as 2 squares of distance. If the far edge of a square is within the spell's area, anything within that square is within the spell's area. If the spell's area only touches the near edge of a square, however, anything within that square is unaffected by the spell.
(The diagram and text are from Pathfinder, but these rules have not changed since 3.5.)
So, the best way to interpret this is to go back to the 3.5 version of D&D. In 4th Edition, there were no circular spell effects. Everything was a square to make things simple for the players and DM. Fifth Edition is going back to the earlier style of play where circles are more common, but on a grid, a circle isn't a circle at all (and they are not like the earlier poster submitted).
The "interpreted" circles are in the older Player's Handbooks and DM Guides, and they have been put up on the net in a number of places.
Here is one of the better guides that comes directly from an earlier stack exchange query (image below): What is a radius on a square grid?
And here is another PDF that one can cut for use on a battle map: http://www.enworld.org/forum/showthread.php?276089-Area-of-Effect-Templates
These exact templates are very likely to appear in the 5e Dungeon Master's Guide when it is out in November/December.
Best Answer
Each 5' square actually takes up 25 square feet (5' x 5'). So you could divide up the 241/25 to get roughly 10 squares, or you could figure out the original length and width and divide each of those by 5' (and round up I guess).