The conversion rate is 1-1 since one balboa has been pegged to $1 since at least the 1930s (in the early 20th century, a Balboa was almost $2). I have come across 1/4 balboas too, and actually thought about spending them in the pop machine at work! I believe they still have 1/10th, 1/4 and 1/2 Balboas that are the same as our coins, not sure about the nickel though. I think they are now using a small coin for 1 balboa, though it used to be identical in every respect to the silver dollar, 26.73 grams 0.900 fine silver!