United States Postal Service offers several mail classes that vary in shipping time and price. First class is the most economical shipping method, but it does not guarantee a delivery date. Endicia, our sponsor, did not have a tool that could accurately predict when first class packages would deliver. This project produced a validated prototype that forecasts delivery time distributions using conditional probability. The results showed that shipping times highly depend on when a package was originally dropped off. Ultimately, this prototype can help Endicia’s business clients greatly optimize their shipping costs.