Given the conservation of matter, one pound.

Given that no system is perfect, the weight of bacon post cooking depends entirely on the amount of fat present in the bacon, the length of time the bacon is cooked and whether you are including the grease leftover in the pan after cooking.

In general, bacon consists of 40-60% fat. If you cook it to a burnt crisp, you'll likely have half or less of the weight of the bacon you started with. If you cook until you reach a rubbery texture, you'll probably lose closer to only 30-40% of the bacon's original weight.