Sorry, I didn't check the knowledge base before posting. Here's what it says:
At an average thickness the kits will plate approximately:
4oz Gold - 0.5 - 1 sq ft
4oz Silver - 1 sq ft
8oz Nickel - 2 sq ft
8oz Copper - 2 sq ft
8oz Copy Chrome™ - 2 sq ft
8oz Bronze - 2 sq ft
8oz Tin - 2 sq ft
4oz Brass - 1 sq ft