Here is some information regarding D&D coins. I started with the official D&D information and expanded on it. I use this information in my games.

10 Copper pieces (cp) = 1 Silver piece
10 Silver pieces (sp) = 1 Gold piece

2 Electrun pieces (ep) = 1 Gold piece
10 Gold pieces (gp) = 1 Platinum piece (pp)

All coins are the same size and the same weight regardless of the type.

1 Coin

• 1 1/4″ Dia.
• 1/10″ Thk.
• 1/3 oz. (50 to a pound)

10 Coins

• 1 foot long when placed in a line
• 1″ tall when stacked

50 Coins

• 1 pound

100 Coins

• 1 square foot when placed in a 10 coins long x 10 coins wide grid

120 Coins

• 1 foot tall when stacked

12,000 Coins

• 1 cubic foot stacked 10 coins long x 10 coins wide x 120 coins tall
• weighs 240 pounds

Trade Bars

• Size: about 5″ x 2″ x 1/2″
• Weight:
  • Silver 2 lb
  • Gold 5 lb
• Value:
  • Silver 10 gp
  • Gold 250 gp
• 288 bars per cubic foot

Dragon Bed of Coins
Dragon Size	Minimum Number of Coins
S	12,000
M	12,000
L	50,000
G	100,000

Piles of coins (cone shaped)
Diameter	Light Pile		Heavy Pile
	Hight in center	Number of Coins	Hight in center	Number of Coins
5 ft	1″	5,000	3″	18,000
10 ft	3″	40,000	6″	156,000
15 ft	4″	135,000	9″	528,000
20 ft	5″	320,000	1 ft	1,260,000

Less that 100 coins per square foot is a scattering of coins.
From 100 coins per square foot to a light pile is a covering of coins.
A pile can range anywhere between a light and a heavy pile.
Adding more coins to a heavy pile increases it’s height and diameter.
In an enclosed area, if there are enough coins they will spread out over the the floor to the walls and fill the available area to 12,000 coins per cubic foot.