USPS Tutorial: How To Save Postage

It’s been over a decade since the U.S. Postal Service changed its price structure to shape-based pricing. That doesn’t mean that the USPS has gotten better at explaining its not-so-new rate system to customers. Their website provides postage rates, but won’t provide guidance to develop postage-efficient packaging strategies. Once you understand the basics below, you can make better money-saving choices

1. Weight a minute.

Prior to 2007, weight was the only thing that mattered when it came to how much you paid. Not anymore. Weight is still a factor, but dimensions, thickness and flexibility are now as important, if not more so.

2. Know Your Categories

First-class mail falls into three categories*: “Letter”, “Flat” and “Parcel” (from cheapest to most expensive). The cheat sheet below nails down the specifics of each mail category, which will put you way ahead of the game. Pay particular attention to thickness requirements.


6.125 ” x 11.5″ max; .25″ max thickness; 3.5 oz. max. Must meet flexibility standards (see below).  Price starts at $.44.

Flat/Large Envelope

12″ x 15″ max; .75″ max thickness; 13 oz. max. Must meet flexibility standards. Price starts at $.88.


12″ x 12″ x 12″ max. Price starts at $1.71. A large package exceeding these dimensions costs even more.

*The postal industry terms for the three categories are letter/flat/parcel. However, the USPS has decided to change these names on their website to letter/large envelope/package.  Same thing.

3. Be Flexible.

Place your mailer halfway off a table’s edge. Lean on the part hanging off the table. Does it give easily? If there’s a solid object inside, your package automatically won’t pass.

But let’s say you’ve got two soft-covered books. If you package them side by side in a mailer instead of stacking them, does your package flex? Your mailer just moved from the “Parcel” to the “Flat” category. Postage savings? $.83.

4. Think Backwards

Design your mailing to meet the above specifications. I once received a 9.5″ x 7″ cocktail party invitation from a non-profit (which makes it a “Flat”). Had the designer created a 6×9 invitation or one that could have folded in half, it would have been a “Letter”. Postage savings? $.44 per invitation.

  • Thickness and weight considerations should influence your page count and your paper stock weight to avoid disqualifying for the “Letter” category.
  • Adding a small solid object like a pen to your mailing not only flunks the flex test, but it also makes it a “Parcel”, increasing postage by more than $1.37!

5. Select your envelope or package to meet above specifications.

Again, weight should not be your top consideration. Thickness and flexibility should be.

  • Don’t add thickness to your mailer unless absolutely necessary (i.e., bubble mailers add thickness).
  • Don’t choose a rigid, corrugate-like material unless absolutely necessary (i.e., a small box is always a “Parcel” because it won’t flex).
  • Don’t choose a grossly oversized envelope or polybag because the thickness differential throughout the package may be too great to qualify as a “Flat”.

For high quality, durable mailers engineered to save money with the U.S. Postal service shape based pricing structure, Best Mailer has you covered.

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