The weight of a standard envelope is 6.75 grams when empty. With contents, FedEx has a maximum weight of 17 ounces, while the maximum weight for USPS mail is 13 ounces. However, the weight of a standard envelope can vary based on the envelope used.
Some mail delivery companies, such as USPS, charge for mail services based on the weight of mail. Certain items cannot be sent by mail, such as alcoholic beverages. There may also be a maximum size when sending documents. As of August 2014, FedEx's maximum size for documents is 8.25 inches x 11.75 inches. The maximum number of pages is approximately 60.