How much postage to mail a 9x12 envelope weighing 14 ounces?

To mail a 9x12 envelope weighing 14 ounces within the United States, you would typically need to use Priority Mail. As of my last update, the cost for Priority Mail starts at around $8.70 for a package of that weight, though prices may vary based on the specific destination and any additional services you select. It's best to check the United States Postal Service (USPS) website or visit your local post office for the most accurate and current pricing.