Posts Tagged Flat

USPS Classifications Of Mail – Part 2

Is It A Letter Or A Flat – Part 2

Last week we delved into the basics of letters and postcards. This week we will review the abundance of information regarding flats and parcels.  It’s a lot, so hold on to your hats!


A flat is described as a rectangular or square piece of mail that is too big in at least one direction to be a letter. That is, larger than 6 1/8” or 11 ½” or thicker than ¼”.

Just to confuse matters more, the mail piece cannot have a side longer than 15”, a side shorter than 12”, is not thicker than ¾” and does not weigh more than 13 ounces for First Class mail or 16 ounces for Standard Class.

USPS recently changed the rules for flats and all pieces must now meet certain flexibility standards. There is a complicated test to determine flexibility; it is always wise (and suggested!) that you discuss this with either your local Postmaster, Business Mail Analyst or your mail presort vendor.

Significantly higher postage rates are charged for mail pieces that don’t meet these flexibility requirements. This would include items such as CD, DVD or boxes. Pieces too rigid to qualify as flats are generally categorized as parcels.

Periodicals get their own special class and must meet requirements to fit one of two sorting processes. They, too, fall into either machinable or nonmachinable catagories.

Standard Class has a category not flat-machinable (NFM). This is a piece that would normally be a flat, with the exception that it does not meet flexibility requirements. This includes boxes, CD/DVD or anything with a non uniform thickness.

Not flat-machinable mail pieces have a higher postage rate because they must be sorted by hand.


As with other mail classes, there are two groups of parcels – machinable and nonmachinable.

A machinable parcel is regular in shape (not including tubes, rolls, etc) and is able to be processed on automated sorting equipment. These mail pieces are also too large or rigid to be considered a flat.

Must meet all of the following:

  • Must be at least 6” Must meet all ofbut not more than 34” AND
  • Height must be at least 3” but not more than 17” AND
  • Thickness must be at least ¼” but no more than 17” AND
  • Must weigh at least 6 ounces but not more than 35 pounds (except books and printed matter, which cannot be more than 25 pounds).

Irregular parcels may includes most everything that cannot be called a letter, flat, NFM or machinable parcel. This includes rolls, tubes and anything else that is too big or too irregular to be sorted on automated equipment.

An Outside parcel exceeds the size limitations of machinable parcels. This includes tubes or rolls longer than 26”, strapped boxes, metal or wood boxes, cartons containing 1 or more gallons of liquid and other out of the ordinary pieces.

It bears repeating, your best action is always checking with your local Postmaster, Mail Acceptance Analyst or presort mail vendor. 

Strahm Customer Service Representatives are available and knowledgeable in answering all your mail piece questions!


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USPS Classifications of Mail

Letters or Flats?

letterpcUSPS terms for defining classifications of mail can be confusing.  These classifications are based on the size and shape of the mail piece; not only do they determine postage, but they are routed across the country in a different manner as well.

When you are preparing your mail piece, it is important to know what classification your mail fits into since this will directly impact your postage budget.

Letters – machinable and nonmachinable
Flats – machinable and nonmachinable
Machinable parcels
Irregular parcels
Outside parcels


  • Height is at least 3 ½” and no more than 6 1/8”
  • Width is at least 5” and no more than 11 ½”
  • Thickness is at least 0.007 and no more than ¼”

Letters that can be sorted on automated equipment are eligible for better postage prices than those that are nonmachinable.

Machinable letters meet all of the criteria above and

      • Weigh no more than 3.3 ounces
      • Are rectangular in shape – it should meet the aspect ratio, which can be determined by dividing the length by the height.  Aspect ratio should be not less than 1.3 or more than 2.5.

Examples of nonmachinable letters include

      • Weight of more than 3.3 ounces
      • non-rectangular
      • enclosed in any type of plastic material
      • includes strings/buttons/clasps
      • contains items such as pens, coins or keys which cause the thickness of the mail piece to be uneven
      • too rigid to meet flexibility requirements
      • has the address placed the same direction as the shortest side of the mail piece instead of the longest side,
      • is a selfmailer with the folded edge perpendicular to the address
      • is a booklet that does not meet USPS

Barcoded mail pieces are eligible for discounted postage rates and must meet additional requirements beyond those for machinable letters.  Always check with your mail vendor for eligibility.


Special postage rates are given only for First Class postcards meeting eligibility.  There is no postcard rate for Standard Class.

Eligibility for First Class postcard price include:

      • Rectangular in shape (see how to determine aspect ratio above)
      • At least 3 ½” high and not more than 4 ¼” high
      • At least 5” long and no more than 6” long
      • Thickness is at least 0.007” and no more than 0.016”

Cards larger than outlined above should use Standard Class letter or flat pricing, depending on the size of the card.

This covers the very basics of letters and postcards.  Next week we will address the confusing world of flats!

As always, if you have questions or want additional information, our Customer Service Representatives are here to serve you.

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USPS Update | Rate Increase January 27th, 2013

Increased 2013 Postage Rates – Effective January 27, 2013

Less than a year ago the USPS increased postage rates a penny and rates are going up again in 2013. Overall, prices will increase an average of 2.6 percent for each class of mail. The Postal Service filed new mailing service prices with the Postal Regulatory Commission (PRC) in October 2012 and the changes were approved within the next month. By law, USPS cannot increase mailing service pricing no more than the rate of inflation, based on the Consumer Price Index. A completely self-supporting government enterprise, the U.S. Postal Service is the only delivery service that reaches every address in the nation. The Postal Service receives no tax dollars for operating expenses and relies on the sale of postage, products, and services to fund its operations.

Highlights of the pricing changes include:

– First-class letters will increase one cent up to 46 cents usps2013
– First-class postcard will increase by one cent to 33 cents
– Flats will increase by two cents to 92 cents
– International first-class pricing will change to one flat rate of $1.10 to any destination in the world. The USPS has also introduced a new Forever stamp for international use, called the Global Forever stamp. This new stamp will always be sold at the price of a single-piece first class international stamp.
– Forever stamps also will still be available and can be used whenever they are needed, as they don’t have a denomination. Forever stamps will also increase to 46 cents.

Several new shipping services products will be available in January as well as increased pricing. New domestic retail pricing for Priority Mail Flat Rate products include:

–   Small Box – $5.80
–   Medium Box – $12.35
–   Large Box – $16.85
–   Regular Envelope – $5.60
–   Legal Envelope – $5.75
–   Padded Envelope – $5.95

Prices for other mailing services including Standard Mail, Periodicals, and other business class mail will also see price increases in a variety of categories. For more detailed pricing information from the USPS visit Still need more? Strahm also offers a Customer Resource Center containing up to date information regarding the January 27th rate increase and much more!

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USPS Guidelines For Flat Size Mailpieces

Designing for Automation Flats!

Last week we discussed designing letters and postcards for automation postage rates.  Below are guidelines for producing flat size mailpieces.

But first! What is the upside to creating automatable mailpieces?

Automation Benefits:

  • Greater postage discount
  • Faster mail processing
  • Better, more consistent service

A flat is described as a rectangular and smooth piece of mail that is too big in at least one direction to be a letter.  The length of a flat size mailpiece is the longest dimension.  The height is the dimension perpendicular to the length.

Flats qualify for automation prices if they meet specific addressing, barcoding and design standards.  Remember that beginning January 28, 2013 your maipiece must use an Intelligent Mail Barcode to be eligible for automation postage discounts.

Designing for Automation Flats:

  • Physical Characteristics
    • Minimum height is 5”
    • Maximum height is 12”
    • Minimum length is 6”
    • Maximum length is 15”
    • Minimum thickness is .009”
    • Maximum thickness ¾”
    • Weight limits
      • First Class not more than 13 ounces
      • Standard less than 16 ounces
  • In addition
    • Must meet specific flexibility standards
    • Must be uniformly thick so that any bumps, protrusions, or irregularities do not cause more than ¼” variance in thickness.
    • Must be rectangular in shape
  • Barcode Standards
    • Must be at least 1/8” from any edge on the address side of the mailpiece
    • Minimum clearance between the barcode and any information line above or below it within the address block must be at least 0.040” for POSTNET and 0.028” for an IMb (IMb is mandatory beginning January 28, 2012)
    • Window Envelopes and Address Labels
      • Minimum clearance between printing and any left or right edge of the window must be 1/8”
      • Minimum clearance between printing and top or bottom of the window must be 1/25”
  • Address Standards
    • Must be within top half of mailpiece
    • A vertical address may cross midpoint if it begins or ends within 1” of top edge (important for small flats)
    • Must be on same side as postage
    • Flats using the Intelligent Mail barcode may use 6 point type for address if it is printing in all capital letters
    • If  there is no Intelligent Mail barcode, minimum type size is 8 point.
  • Address Format

Sue Sample

ABC Company

123 Main Street

Anytown, MO  ZIP+4

  • Address Tap Test (address readability through envelope window)
    • Mail using a window envelope must show complete address, with 1/8” clearance at top, bottom and both sides of window
    • Test address placement with two taps on bottom and two taps on each end – address should remain within window with 1/8” clear space
  • Print Contrast
    • Preference is dark type on light paper
    • Recommend light pastels or neutrals
    • Avoid dark, bright or black papers
    • Avoid dark fibers
    • Avoid bleed through

What steps will you take today to ensure your mail is automation compatible? Don’t lose out on reduced postage rates for automation mail!

If you have questions or need more information, please contact one of Strahm’s Customer Service Representatives.  They can be reached at or (816) 756-2733.

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