First-Class Mail service is an affordable and easy way to send envelopes and postcards. First-Class Mail Forever stamps cost $0.82 (the current 1 oz price) and will never expire, even if the First-Class postage rate goes up. To send packages, see USPS Ground Advantage service.

First-Class Mail service is an affordable and easy way to send envelopes and postcards. First-Class Mail Forever stamps cost $0.82 (the current 1 oz price) and will never expire, even if the First-Class postage rate goes up. To send packages, see USPS Ground Advantage service. Features & Pricing: - Mail delivered in 1–5 days - Our best-priced service for items up to 13 oz - Postmarking & Proof of Mailing: Ask a retail associate at a Post Office retail counter to hand-cancel mail for free to ensure postmarking on the day mailed. Certificate of Mailing available for an extra service fee. - Proof of Delivery: First-Class Mail items are eligible for Delivery Confirmation services such as Certified Mail. - One price for up to 3.5 ounces with commercially priced letters and cards - Prices based on shape and weight Standard Pricing: Letters: Standard-sized, rectangular envelope stamps start at $0.82. Square, oversized, or unusually shaped envelope stamps start at $1.31. Postcards: Standard-sized, rectangular postcard stamps start at $0.65. Oversized postcards need letter stamps, which start at $0.82. Large Envelopes: Large envelopes (flats) start at $1.69. Weight, Size, & Shape Requirements: - Maximum weight for First-Class Mail letters is 3.5 oz; for large First-Class Mail envelopes, the maximum weight is 13 oz. - All postcards and envelopes (or flats) must be rectangular, otherwise an additional charge may apply. Additional Charges: Nonmachinable Envelopes: Unusually shaped mail like square or vertical envelopes, lumpy envelopes, rigid envelopes, and mail with clasps, string, or buttons must be hand-canceled and are charged a nonmachinable surcharge even if they weigh less than 1 oz. Large Mailpieces: Letters exceeding standard envelope maximum dimensions are charged large envelope (flat) prices. Large Envelopes treated as Small Packages: Large First-Class envelopes that exceed maximum dimensions or are rigid, non-rectangular, or not uniformly thick are charged package prices and shipped with USPS Ground Advantage. For Businesses: USPS offers data-driven shipping with commercial prices and automation discounts. First-Class Mail commercial pricing is available for presorted letters and flats with a minimum quantity of 500 mailpieces. Automation discounts may apply. One price up to 3.5 oz available for presort and automation compatible letters and cards.