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Quick Service Guide 301

Discount Flats

Physical Standards for Discount Flats

May 2007
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Flat Dimensions

r greater than 3/4 inch thick.

11-1/2 inches
15 inches
6-1/8 inches
12 inches
1/4 inch
3/4 inch
* Flats exceed at least one of these dimensions

For physical standards of automation flats, see Quick Service Guide 301a.

In addition to shape, the Postal Service classifies mailpieces by the way they are prepared. These classifications are based on how efficiently your mailpieces can be processed on Postal Service equipment. The Postal Service classifies discount flats as either nonautomation or automation flats.

A flat meets automation standards and qualifies for automation rates if it meets the specific addressing, barcoding, and design standards. Automation rate flats must have a delivery point barcode, ZIP+4 barcode, or an Intelligent Mail barcode.

Dimensions, Shape, Flexibility, and Uniform Thickness (301.1.0)

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  • Minimum: more than 11-1/2 inches long, or more than 6-1/8 inches high, or more than 1/4 inch thick.
  • Maximum: 15 inches long, 12 inches high, and 3/4 inch thick.

The length of a flat-size mailpiece is the longest dimension. The height is the dimension perpendicular to the length.

Shape: rectangular.

Flexibility: flat-size piece must meet flexibility criteria in 301.1.4.

Uniform thickness: the contents must be uniformly thick so that any bumps, protrusions, or irregularities do not cause more than 1/4 inch variance in thickness (301.1.5).

Mailpieces that do not meet the standards for shape in 301.1.3, or for flexibility in 301.1.4, or for uniform thickness in 301.1.5, must pay applicable rates as follows:

  • First-Class Mail—parcel rates.
  • Standard Mail—Not Flat-Machinable or parcel rates.
  • Bound Printed Matter—parcel rates.

Presorted Nonautomation Flats (301.2.0)

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Maximum weight:

  • First-Class Mail: 13 ounces.
  • Standard Mail: less than 16 ounces.
  • Bound Printed Matter: 15 pounds.

Automation Flats (301.3.0)

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Flats may qualify for the automation discount based on the physical standards in 301.3.0. Periodicals automation flats may also qualify under alternative criteria in 707.25.3.

See Quick Service Guide 301a, Designing Flats for Automated Processing, for an overview.

Standard Mail Not Flat-Machinable Pieces (401.2.2)

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For Standard Mail Not Flat-Machinable pieces, see Quick Service Guide 401.

For the specific DMM standards applicable to this category of mail, consult the DMM sections referenced above and the general sections within each DMM module.

Quick Service Guides

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First-Class Mail

See Quick Service Guides:

330a Nonautomation Flats

330b Automation Flats

Standard Mail

See Quick Service Guides:

340a Nonautomation Flats

340b Automation Flats

340c Enhanced Carrier Route Flats

Bound Printed Matter

See Quick Service Guide:

360 Flats

Media Mail

See Quick Service Guide:

370 Presorted Flats

Library Mail

See Quick Service Guide:

380 Presorted Flats


See Quick Service Guides:

707e Nonautomation Flats

707g Automation Flats


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