Dimensional Standards
Mail Piece Dimensions
Letters
Size Limits:
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Rectangular; length is the dimension parallel to the address with aspect ratio between 1.3 and 2.5. Length divided by height.
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At least 3.5 inches high by 5 inches long by .007 inch thick
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No more than 6-1/8 inches high by 11-1/2 inches long by 1/4 inch thick
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Up to 3.5 ounces
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Surcharge will apply for non-machinable letters. Currently, $0.20 per piece.
Flats
Size Limits:
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Rectangular
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No more than 12 inches high by 15 inches long by .75 inch thick
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Must not be rigid and must be uniformly thick.
Parcels
Size Limits:
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No more than 108 inches in combined length and girth.
Postcards
Size Limits: Single thickness cannot be folded
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Minimum: 3-1/2 inches high by 5 inches long by 0.007 inch thick
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Maximum: 4-1/4 inches high by 6 inches long by 0.016 inch thick
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Additional postage is required by the USPS for larger postcards. Contact Postal Services for current piece rate.
