Weight first class mail
The weight limits for First Class Mail in the United States are as follows:
Letters
- Weight: Up to 3.5 ounces (99 grams)
- Size: Maximum dimensions of 11.5 inches (29.2 cm) long, 6.125 inches (15.6 cm) wide, and 0.25 inches (0.64 cm) thick
Large Envelopes (Flats)
- Weight: Up to 13 ounces (368 grams)
- Size: Maximum dimensions of 12 inches (30.5 cm) long, 15 inches (38.1 cm) wide, and 0.75 inches (1.9 cm) thick
Packages
- Weight: Up to 13 ounces (368 grams)
- Size: Maximum dimensions of 12 inches (30.5 cm) long, 12 inches (30.5 cm) wide, and 2 inches (5.1 cm) thick
Special Handling
- Weight: Up to 70 pounds (31.8 kg)
- Size: Maximum dimensions of 108 inches (274.3 cm) long, 165 inches (419.1 cm) wide, and 108 inches (274.3 cm) tall
Note that these weight limits apply to the total weight of the mailpiece, including any packaging materials, such as envelopes, boxes, or wrapping.
It's also important to note that First Class Mail has a maximum thickness of 1/4 inch (0.64 cm) for letters and 3/4 inch (1.9 cm) for large envelopes and packages. If your mailpiece exceeds these thickness limits, you may need to use a different class of mail, such as Priority Mail.