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Quick Service Guide 301

Commercial Flats

Physical Standards for Commercial Flats

January 2, 2011
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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 commercial flats as either nonautomation or automation flats or machinable and nonmachinable for Periodicals.

A flat meets automation standards and qualifies for automation prices if it meets the specific addressing, barcoding, and design standards. Automation flats must have a POSTNET or Intelligent Mail barcode with a delivery point routing code.

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, with four square corners, or with finished corners that do not excced a radius of 0.125 inch (1/8 inch).

Flexibility and deflection: flat-size pieces must meet flexibility criteria in 301.1.3 and the deflection criteria in 301.1.6. Flats mailed at saturation or high density prices or flats mailed at basic carrier route prices and dropshipped to DDUs do not have to meet deflection standards. All other flats not meeting deflection standards are subject to prices as stated in DMM 301.1.7.

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 (301.1.4). When determining variance in thickness, exclude the outer edges of a mailpiece (1 inch from each edge) when the contents do not extend to the edges.

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

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

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.

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

Standard Mail Not Flat-Machinable Pieces (401.2.4)

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

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 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 Nonmachinable Flats

707g Barcoded (Automation) Flats


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