A Complete Guide about Square Envelope Postage 🔥 !

Square envelopes are mostly used for advertising, Greeting cards, and invitations. Square Envelopes have their unique shape, Look modern, and more durable than other envelopes.

How much does it cost to mail a square envelope Postage?

Square Envelope, Oversized, or unusually shaped envelope will cost you an extra $0.20 per letter. For a 1oz standard Envelope or Rectangular Envelope, normally it requires a $0.55 stamp. Letters which are Squared type considered as Odd Sized, which results in higher prices for Postages.

Above are the standard USPS postage rates. You can see more updated rates on their official site as well. So addition of Extra 20 cents, Square envelope total cost will be ( $0.20 + $0.55 = $0.75 ) even if they weigh less than 1 oz or equal to 1oz.

  • For 2oz Square Envelope letter its will be ($0.75 + $0.20 = $0.95).
  • For 3oz Square Envelope letter its will be ($0.95 + $0.20 = $1.15).

Want to know about how many stamps do i need

Why Square Envelope Postage costs some extra Cents?

According to USPS, Rectangular Envelopes are processed in a short period. Because an envelope can be grabbed by one of its longer sides, the machine can easily locate its upper and Lower end Corner.

It’s easy for a machine to read the address and route the person’s envelope easily. On the other hand, Square envelopes do not have a long side to land on the machine automatically. The machine will need some extra steps to adjust the envelope and read it easily. But it’s easy for a machine to remove a square envelope from the sorter.

Human involvement is necessary to put the address into the system manually so that it may be routed to the correct post office. So that’s why there is a $.20 surcharge due to the non-machinable envelope for the first Oz.

Characteristics of Non-Machinable or Odd Sized Letters

  •     Square type envelops
  •     Rigid Envelopes
  •     Lumpy Type Envelopes
  •     Envelopes wall thickness more than 1/4″
  •     Vertical Type envelopes
  •     Envelops that have strings and clasps

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Square Envelope Sizes


Envelope Type Size in Inches Size in Millimeter
5 Square 5 x 5 127 x 127
5 1/2 Square 5.5 x 5.5 140 x 140
6 Square 6 x 6 152 x 152
6 1/2 Square 6.5 x 6.5 165 x 165
7 Square 7 x 7 178 x 178
7 1/2 Square 7.5 x 7.5 190 x 190