Large Envelopes (flats), under 16 ounces (the actual weight limit is 15.994 ounces to accommodate Postal Service systems that round to three decimal places and thus round items that weigh 15.995-15.999 ounces up to 16 ounces).Ĥ First-Class Package International Service maximum weight: 4 lbs. Medium and Large Flat Rate Boxes, 20 lbs.ģ First-Class Mail International maximum weights: Letters, 3.5 ounces. Prepare Now: Starting March 1, 2023, packages sent to countries that follow European Union (EU) customs rules will need more-detailed content descriptions for customs forms. Complete tables of prices are available in Notice 123, Price List.ġ Priority Mail Express International Flat Rate Envelopes maximum weight: 4 lbs.Ģ Priority Mail International Flat Rate Service maximum weights: Flat Rate Envelopes and Small Flat Rate Priced Boxes, 4 lbs. For sending letters under 3.5 oz and large envelopes under 15.994 oz to other countries, see How to Send a Letter: International. Listed below are the countries and their price groups and weight limits for the five principal categories of international mail. USPS Marketing Mail Eligibility Decision Tree.

Designing Letter and Reply Mail (PUB 25).

Usps flat rate box sizes international