You will find a wide selection of envelopes in both online and local stores. These envelopes can come in various forms, shapes, and sizes. #6 3/4 Envelopes can be considered as one of the popular envelopes used for various purposes for both personal and official uses. #6 3/4 Envelopes are generally white in color with an approximate weight of 24lb. These envelopes are rectangular in shape with a measurement of six and a half inches in width by three and five-eighth inches in height. The size of a standard #6 3/4 Envelope is perfect for inserting it inside #9 and #10 envelopes.