How much to mail an 8x10 envelope weighing 1lb 8oz?

To mail an 8x10 envelope weighing 1 lb 8 oz within the United States, you would typically use the USPS. As of my last update, the cost for a First-Class Package Service for a package of that weight would be around $5.00 to $6.00, depending on the specific destination and any additional services like tracking or insurance. For the most accurate pricing, it's best to check the USPS website or visit your local post office.