In the case of the comparison between USPS, FedEx and UPS we can see varying data for different packages. Thus, the cheapest variant for packages of less than 10 lbs, envelopes, lightboxes, expedited International and priority International shipping USPS is the cheapest. FedEx is the cheapest in case of over 10lbs packages, heavy boxes, two-day shipping, Next-day shipping (AM and PM), priority International and overnight shipping. UPS is suitable for Over 10lbs (Standard) packages, heavy boxes, two-day shipping and next-day shipping (PM).