As of 2015, the U.S. Postal Service offers two sizes of flat-rate boxes for Express one-to-two-day delivery. It also offers five sizes of flat-rate boxes for Priority one-to-three-day delivery. More »

A USPS Flat Rate Box offers one low flat rate, so pricing is determined by the size box you choose rather than the weight of the box or the destination of the package. More »

www.reference.com Business & Finance Mail & Shipping Postal Services

The United States Postal Service provides tracking options for most packages and letters shipped to Canada. The USPS does not, however, ship or track Priority Mail International Fat Rate envelopes or small Flat Rate ship... More »

A USPS Flat Rate Box offers one low flat rate, so pricing is determined by the size box you choose rather than the weight of the box or the destination of the package. More »

www.reference.com Business & Finance Mail & Shipping Postal Services

UPS flat-rate boxes range in dimensions from 18 inches by 13 inches by 3 inches for the largest box to 13 inches by 11 inches by 2 inches for the smallest box. The medium-sized box is 16 inches by 11 inches by 3 inches. More »

The U.S. Postal Service only sells flat-rate boxes for the purpose of sending Priority Mail. The Postal Service designates all other packages Parcel Post, now renamed Standard Post. It charges set prices for Priority Mai... More »

United States Postal Service regional-rate boxes differ from standard flat-rate boxes in one major way. The costs for regional-rate boxes depend on the size of the box and the shipping zone, rather than having a single f... More »

www.reference.com Business & Finance Mail & Shipping Postal Services