First-Class Mail Letters  
First-Class letters, a cost effective and simple way to mail.
Use a stamp, postage meter, or PC postage and drop the letter in a collection box or hand it to your carrier.

First-Class letter dimensions:

Rectangular
At least 3-1/2 inches high X 5 inches long X .007 inch thick
No more than 6-1/8 inches high X 11-1/2 inches long X 1/4 inch thick
Maximum weight is 3.5 ounces
Letters that are considered nonmachinable are subject to a surcharge.
Length is the dimension parallel to the address.


 
Calculate Postage
Find out how much First-Class Mail costs.
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Add Extra Services:

Proof at Deposit
Certificate of Mailing – Provides evidence of mailing.
Certified Mail™ – Provides a mailing receipt and online access to delivery information.
Collect on Delivery – Allows the postage and price of an item to be collected from the recipient by the USPS and given to the mailer.

Protection in Transit
Insured Mail – Insurance against loss or damage for merchandise and gifts.
Registered Mail™ – Provides maximum security and date of delivery or attempted delivery.

Related Publications
A Customer's Guide to Mailing – A simple, easy-to-understand guide to mailing in the U.S.
First-Class Mail postage rates