First-Class Mail

Picture of First Class Stamps

1-3 Business Days

First-Class Mail® is an affordable way to send envelopes and lightweight packages. First-Class Mail Forever® stamps are sold at the current 1 oz letter rate but don't expire even if the stamp price goes up.

Stamp Prices


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


  • Standard-sized, rectangular postcard stamps start at $0.35.
  • Oversized postcards need letter stamps, which start at $0.55.
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First-Class Mail® prices are based on size, shape, and weight.

Size & Weight Requirements


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 weigh less than 1 oz.

Larger Envelopes

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

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

Price Calculator Wizard

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

Calculate a Price First-Class Mail Prices


  • Best priced service for mail up to 13 oz
  • Delivery in 1 to 3 business days
  • Insurance for loss or damage up to $5,000 for merchandise only
  • Can combine with extra services to confirm delivery
  • Get up to 3.5 ounces free with commercial priced letters and cards

See Insurance and Extra Services Details

For Businesses

First-Class Mail is targetable, trackable with certain extra services, and measurable — offering a wide range of options for businesses. With address correction and forwarding services, your message reaches a greater percentage of your audience.

Commercial Prices

Commercial pricing is available for presorted letters, flats, and packages with a minimum quantity of 500 mailpieces. Automation discounts may also apply.

Calculate Volume Prices


One Price Up To 3.5 Ounces

Pay one price for up to 3.5 ounces for First-Class Mail presort and automation compatible letters and cards 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 to First-Class Mail single-piece letters.

3.5 Ounce Free Fact Sheet (RTF | 125 KB)
Requirements for Automation Discounts


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.

Learn More About Preparing Your Shipment

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

See All Restrictions