Buffalo, NY, North Eastern US, NYC and Pittsburgh, PA, company options for style and size envelopes

There are many different envelopes available to use. They differ by size, flap type and the many window positions. Below are images and information about our recommended envelopes for direct mail marketing in Buffalo, Pittsburgh and other surrounding areas.


There are various parts of an envelope. Variations of these parts create different envelope styles.


The envelopes with the opening and seal slap located on the SHORT dimension are called Open End envelopes. The ones with the flap on the long dimension are called Open Side envelopes. These envelopes are ideal for automatic insertion applications.

Remember, not all envelopes are machine friendly. When you choose an envelope that is machine friendly you save time and money. If you are unsure, please call PDM to discuss.

Flap Styles

The flap is the part of the envelope that is folded to seal it. The main flap shapes are shown.

Remember, certain flap shapes and sizes can make an envelope not machine friendly. As always if you are unsure, please call us at PDM to discuss.

Sizes and Styles

There are two main envelope standard systems. The first is used in Buffalo, Pittsburgh and the rest of the United States. (US envelopes are often referred to as Standard.) The other is the ISO metric system used in Europe and other parts of the world.

Envelope sizes vary from very small to very large and there are many sizes in between. Here are a few of the commonly used sizes. (Sizes are listed in inches and the shortest dimension is first.)


These are the most popular envelopes for business correspondence. They have a commercial flap style.


These are common envelopes used for announcements, invitations, cards, small booklets, brochures or other promotional pieces. Flaps are usually pointed or flat.


These are more formal, deeper envelopes used for announcements, invitations and cards. Flaps are usually pointed.


These envelopes are often used for sending catalogs and folders.


These envelopes are mainly used for sending catalogs, magazines and reports.

There is also metal clasp, coin and other styles not listed here, because they are typically not suitable for printing.


Window envelopes are most often used for bills, checks and marketing purposes. They are very cost efficient since the name and address shows through the window, eliminating the need for additional printing of the address on the envelope.

* It is important to note that the sizes and positions of windows vary greatly depending on the manufacturer.


The most common window size (and recommended by the USPS) is 1-1/8 x 4-1/2, and the position is 7/8 inch from the left and 1/2 or 5/8 inch from the bottom.


These envelopes are often used for checks and invoices. Check, #9 and #10 are the most popular sizes.

For some people, envelope sizes and shapes are easy to select; if you already know what envelope you have in mind, we encourage you to let us know. We are here to serve your Buffalo, NY or Pittsburgh, PA company in any way we can.