A standard legal-size envelope has dimensions of 9.5 by 15 inches. Envelopes labelled as “legal size” are meant to hold documents measuring 8.5 by 14 inches, whether they’re being sent by the mail or being carried in person.
Legal documents are typically sent over the mail using services like the United States Postal Service in paper, paperboard, or manila envelopes. Legal envelopes, in contrast to regular envelopes, may hold multiple sheets of paper. If you need to mail a picture or other flat document that will be damaged if folded, a legal-size envelope is the way to go. Some legal-size envelopes are made of lightweight plastic and are ideal for filing and storing paperwork related to legal matters, whether at the office or at home.