First-Class Mail

1–3 Business Days

First-Class Mail® service is an affordable and easy way to send envelopes and lightweight packages. First-Class Mail Forever® stamps cost $0.55, the current 1 oz price, but will never expire, even if the First-Class postage rate goes up.

Buy Stamps First-Class Mail Prices

Features & Pricing

  • Delivery in 1–3 business days
  • Best priced service for mail up to 13 oz
  • Insurance for loss or damage up to $5,000 for merchandise only
  • 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 size, shape, and weight


  • Standard-sized, rectangular envelope stamps start at $0.55.
  • Square, oversized, or unusually shaped envelope stamps start at $0.70.


  • Standard-sized, rectangular envelope stamps start at $0.35.
  • Oversized postcards need letter stamps, which start at $0.55.

Weight, Size, & Shape Requirements

  • Maximum weight for First-Class Mail letters is 3.5 oz; for large First-Class Mail envelopes and parcels, the maximum weight is 13 oz.
  • All postcards and envelopes (or flats) must be rectangular, otherwise an additional charge may apply. Additional size restrictions apply depending on the type of mailpiece you're sending.

Additional Charges for Irregular Mailpieces & Envelopes

Non-Machineable Envelopes

Unusually shaped mail, like square or vertical envelopes, lumpy envelopes, rigid envelopes, and mail with clasps, string, buttons, must be hand-cancelled. They are charged a non-machineable surcharge even if they weight less than 1 oz.

Large Mailpieces & Envelopes

If a mailpiece exceeds the maximum length, height or thickness, it will be charged at the next higher price and mailpiece category.

Large envelopes (flats) that exceed maximum dimensions, are rigid, non-rectangular, or not uniformly thick are rigid, are charged parcel prices.

The USPS® Price Calculator tool will show you how to measure your envelope and then calculate your domestic postage costs for you.

Calculate a Price

Additional Information

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Mailing Restrictions & Prohibitions

There are specific regulations and standards for mailing restricted, prohibited, and hazardous materials, including cigarettes and smokeless tobacco.

Domestically Restricted & Prohibited Items

Learn more about what items you may and may not mail within the U.S.

Domestic Shipping Prohibitions & Restrictions

For Businesses

USPS understands what's most important to our business customers: speed, affordabililty, security, and customer service. We help businesses provide these services and resources to their customers at discounted rates.

Data-Driven Shipping

First-Class Mail targetable, trackable (with certain extra services), and measurable, offering a wide range of options for businesses. With address correction and forwarding services, your messages will reach a greater percentage of your target audience.

Commercial Prices & Automation Discounts

Bulk Discounts. First-Class Mail commercial pricing is available for presorted letters, flats, and packages with a minimum quantity of 500 mailpieces. Automation discounts may also apply.

Eligibility Requirements for Automation Discounts

One Price Up to 3.5 Ounces. Pay one price for up to 3.5 oz for First-Class Mail presort and automation compatible letters and cards. This is a cost-effective way for businesses to include promotional messages with bills, invoices, and statements. The one price for up to 3.5 oz rate is not a blended rate and does not apply First-Class Mail single-piece letters.

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