USPS® First-Class Mail: Services, Costs, and Delivery Times

Learn everything you need to know about this affordable and easy way to send envelopes and postcards.

What is USPS First-Class Mail?

Use First-Class Mail Forever® stamps

Delivered in 1-5 business days

Send mail pieces to be delivered in 1-5 business days with First-Class Mail.

Great for mailpieces

Send letters, envelopes, postcards, and large envelopes with First-Class Mail.

Discounted Rates

With Stamps.com, you can save up to 8% when using this service

Low prices

First-Class mail is USPS’ best-priced service for items up to 13 oz.

Convenient services

First-Class mail is eligible for Delivery Confirmation™ services such as Certified Mail®.

Overview of USPS First-Class Mail

How fast is First-Class Mail?

First-Class Mail is delivered in 1-5 business days and is eligible for Delivery Confirmation services such as Certified Mail.

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What kind of mail can you send and how much does it cost?

Standard-sized, rectangular envelope stamps start at $0.73 for letters. Square, oversized, or unusually shaped envelope stamps start at $1.19. For postcards, standard-sized, rectangular postcard stamps start at $0.56, and oversized postcards need letter stamps, which start at $0.73. Lastly, large envelopes (flats) start at $1.50.

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What is the maximum weight and required shapes for First-Class mail?

The max 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 must be rectangular, otherwise additional fees may apply. Additional size restrictions apply depending on the type of mailpiece you’re sending as well.

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Pro Tips

How do I calculate domestic postage costs?

Have your mailpiece’s weight, shape, and size measurements on hand, and you can use the USPS Price Calculator tool to easily calculate your domestic postage costs.

What are nonmachinable envelopes?

Nonmachinable envelopes might be non-rectangular, rigid, unevenly thick, or have non-paper closures, meaning they cannot be processed efficiently by USPS’s automated sorting equipment, and require special handling, resulting in a surcharge in addition to the standard postage.

Can large mailpieces be sent with First-Class mail?

Yes, First-Class Mail can handle large envelopes, also known as “flats”, up to 12 inches high, 15 inches long, and 3/4 inch thick, with a maximum weight of 13 ounces. Any envelope exceeding this will be classified and priced as a package, typically sent via USPS Ground Advantage.

Are large envelopes treated as small packages?

Large envelopes are not automatically treated as small packages by USPS. Any envelope up to 12″ high, 15″ long, and 3/4″ thick, with a maximum weight of 13 oz, is considered a First-Class “flat” according to USPS. If a large envelope exceeds these dimensions or is nonmachinable, then it will be treated and priced as a package, typically under USPS Ground Advantage.

What are the prices and features of First-Class mail?

First-Class Mail is an affordable USPS service for postcards, letters, and large envelopes, typically delivered in 1-5 business days. Prices vary by item type, shape, and weight, starting at $0.73 for a 1 oz letter. While it doesn’t automatically include tracking, optional services like Certified Mail can provide it.

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