what is the cheapest way to ship 50 lbs typically depends on the destination and delivery time. For domestic shipping, USPS offers the cheapest option for 50 lbs with Priority Mail, especially if the package can fit within the flat-rate boxes. FedEx Ground and UPS Ground are also reliable, cost-effective services for heavier packages, although rates may vary depending on the distance and service level. For international shipments, checking with each carrier for specific rates based on origin and destination is essential to ensure the lowest cost option is selected for shipping 50 lbs.