Usps first class mail envelope size

According to the United States Postal Service (USPS), the standard size for a First-Class Mail envelope is:

• Length: 3.5 inches (8.89 cm) to 6.125 inches (15.56 cm)
• Height: 5 inches (12.7 cm) to 6.125 inches (15.56 cm)
• Thickness: 0.007 inch (0.1778 mm) to 0.25 inch (6.35 mm)

The maximum weight for a First-Class Mail envelope is 3.5 ounces (99 grams).

It's worth noting that the USPS also has specific requirements for the size and shape of envelopes for certain types of mail, such as:

• International mail: The maximum size for international mail is 11.5 inches (29.21 cm) in length and 6.125 inches (15.56 cm) in height.
• Priority Mail: The maximum size for Priority Mail envelopes is 13 inches (33.02 cm) in length and 12 inches (30.48 cm) in height.
• Large Envelopes: The USPS also has a category for large envelopes, which are defined as envelopes that are larger than the standard First-Class Mail size but smaller than a flat rate envelope. The maximum size for large envelopes is 12 inches (30.48 cm) in length and 15 inches (38.1 cm) in height.

It's always a good idea to check with the USPS for the most up-to-date information on envelope sizes and requirements before sending mail.