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Envelope Basics

Envelope 1 is a premier national envelope supplier, with the experience and expertise to provide solutions for you and your customers. From business envelopes to announcement envelopes and everything in between. Envelope 1 is here to aid you with our knowledge and experience for all your envelope needs.

Components of an Envelope

Regardless of size or variations, an envelope has the same basic parts: corners, flaps, folds, shoulders, throat, seal and seams.

Envelope Face

Envelope Face

Envelope Back

Envelope Back

Components of an Envelope
(1) Seal Flap – The flap normally left open for inserting an envelope’s contents.
(2) Gum Area – The adhesive that seals an envelope.
(3) Top Fold – The fold that creates the seal flap of the envelope.
(4) Back Flap – The back panel of the envelope.
(5) Bottom Fold – The fold at the bottom creating the back flap.
(6) Throat – Space between the top of an envelope’s back flap and its top flap crease line.
(7) Side Flap – The side panels of an envelope.
(8) Side Fold – The fold where the side flaps are folded down.
(9) Shoulder – The part of an envelope where the side flaps crease with the seal flap.
(10) Side seam under – An envelope with its side seam folded under its back flap.

How to Measure an Envelope

Although envelopes are measured from the shortest dimension first, this practice does not distinguish the height from the width. Therefore, if the envelope is placed before you with its seal flap at the top, the dimension from the bottom fold to the top fold is the height. The dimension from the left to right is the width. Simply considering the position of the flap is the first step in describing envelopes.
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How to Measure Window Positions

A window in an envelope is a cut-out in an envelope’s body to show mailing address, return address and/or special messages. Window size is always specified as height x width regardless of orientation. Window positions are always measured by their distance from the left edge (L) of the envelope and the distance from the bottom (B). These standards apply even if you need to measure multiple windows or custom shaped windows.
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