I have gotten 9 yards in a regular flat rate envelope. I folded the fabric and placed it in a plastic bag and sat on it. I did use tape to put on the outside which my local po at the grocery store requres everyone to do. I also sat on the envelope for a little bit before closing it. You can order the legal sized flat rate envelopes from usps.com and they hold more as they are longer envelopes. I lay my fabric out and fold into thirds length-wise, before folding into squares. When I mail fabric to Canada, I mail 6 yard total in a flat rate envelope due to the package cannot weigh over 4 pounds. Hope this helps.