Machinable Letters and Cards

If you prepare your letters and cards so that they have an accurate address and can be processed on Postal Service equipment, your mail is "machinable" and eligible for "presort" rates. Machinable mailpieces must meet specific standards, including size, shape, and weight.

Maximum weight: First-Class Mail and Standard Mail: 3.3 ounces

Machinable letters must not meet any of the non-machinable characteristics

Shape: Rectangular

Dimensions:

Minimum: 5 inches long, 3-1/2 inches high, and 0.007 inch thick.
Maximum for First-Class Mail card rates: 6 inches long, 4-1/4 inches high, and 0.016 inch thick.
Maximum for letters and other cards: 11-1/2 inches long, 6-1/8 inches high, and 1/4 inch thick.

Length is the dimension parallel to the address.

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