[RPG] How does the size of the Gold Dragonborn fire breath weapon work


I know that the gold dragonborn in D&D 5e have a 15ft cone as breath weapon, but is that 15ft radius cone or 15ft diameter cone?

Best Answer

15' long, 15' wide at the end

Cones are described in the PHB (p. 204) at the end of Chapter 10 under spellcasting:

A cone extends in a direction you choose from its point of origin. A cone's width at a given point along its length is equal to that point's distance from the point of origin. A cone's area of effect specifies its maximum length.

A cone's point of origin is not included in the cone's area of effect, unless you decide otherwise.

While confusing because this is under spellcasting and the Dragonborn doesn't use a spell to do this, the mechanics of cones/lines/cubes/cylinders/spheres all rely on the mechanics described in that section.

And in this case, Width is the same as Diameter.