Standard mail sizes

Here are the standard sizes for mail in the United States:

Letters

• Standard letter size: 3.5 inches (8.9 cm) high x 6.125 inches (15.6 cm) long x 0.007 inch (0.18 mm) thick
• Maximum weight: 1 ounce (28.35 grams)

Large Envelopes (Flats)

• Standard large envelope size: 11.5 inches (29.2 cm) high x 6.125 inches (15.6 cm) long x 0.25 inch (6.4 mm) thick
• Maximum weight: 13 ounces (369.3 grams)

Packages

• Small package size: 12 inches (30.5 cm) high x 12 inches (30.5 cm) long x 8 inches (20.3 cm) wide
• Medium package size: 18 inches (45.7 cm) high x 18 inches (45.7 cm) long x 12 inches (30.5 cm) wide
• Large package size: 24 inches (61 cm) high x 24 inches (61 cm) long x 18 inches (45.7 cm) wide
• Maximum weight: varies depending on the shipping carrier and service used

Other Mail Sizes

• Postcards: 3.5 inches (8.9 cm) high x 5 inches (12.7 cm) long
• Catalogs: 6 inches (15.2 cm) high x 9 inches (22.9 cm) long
• Booklets: 5 inches (12.7 cm) high x 7.5 inches (19.1 cm) long

Note: These sizes are general guidelines and may vary depending on the specific mail service or carrier used. It's always a good idea to check with the carrier or mail service for specific size and weight restrictions.