I've put together this simple calculator that will let you enter the number of cards that can complete your meld, and the number of cards remaining in the deck. The number of cards remaining is something that you can guess at from the size of the stock pile in a live game. Online at places like Game Colony, they will tell you how many card remain in the stock pile so you can enter the exact number.
Once you input those two items of information, click "Calculate" and the program will tell you the percentage chance that you will fill in your meld on the net draw.
After experimenting with the program for a little while, you can see how the chances of completing a meld increase as the deck grows smaller. At some point you may use information that you can get from this calculator to decide the point in time where you'd rather wait for Gin than knock with a low deadwood count.

