Like many products, envelopes have a list of special terms to describe various parts and aspects of the manufacturing process.  In previous posts, I’ve explained the difference between open-end and open -side envelopes (the former has the flap on the shorter dimension, the latter on the longer dimension) and other descriptive terms which can cause some head-scratching.

One of the concepts that many buyers find confusing is how to properly measure a window in general and a vertical window in particular.

In order to provide window specs in a way that your envelope vendor will understand, the first thing to keep in mind is the proper orientation of the envelope to be measured.  Much of the confusion in establishing proper specifications for quoting have to do with the fact that certain descriptions like, “the flap is on the side” are relative. It depends on how you’re holding and looking at the envelope. 

So, the first step in measuring a window is to hold the envelope so that the flap is facing toward the sky. When measuring the length and width of the window itself, always state the “north/south” dimension first.  So, for instance on a standard #10 window envelope, the window specs measure and should be described, “1-1/8” x 4-1/2”.

This gets a little tricky when you’re dealing with what we call a “vertical window”. A vertical window is where the longer dimension runs in that “north/south” direction. Remember, you have to be looking at the envelope with the flap pointing north or straight up.  The best example of this is a standard 9 x 12 window envelope. This is a common, stock item for most envelope companies. These envelopes are booklet-style or open-side (different ways to describe the same thing).  The size of the window is 1-3/4” x 4-1/2”.  However when you hold the envelope with flap up top, you’ll notice that the longer dimension of the window actually runs in a vertical direction from the bottom toward the top; hence, it’s name.

So, when you are providing specs for a quote, you would state the window specs with the longer, vertical dimension first; i.e.  “4-1/2” x 1-3/4”.

The second step in specifying a window for quote is to provide the position on the envelope. That is done by measuring in from the left side of the envelope to where the window begins. Then, you do the same thing from the bottom of the envelope to where the window begins.  Once again, this needs to be done by holding the envelope with the flap pointing up toward the sky.  On the standard 9 x 12 window envelope, the window is positioned  2-1/2” from the left side and 7/8” from the bottom.

When this envelope is actually used, the 8 ½ x 11 sheet of paper that contains the mailing address that shows through the window will be oriented in a portrait manner rather than landscape.  That means that when you read the address, the flap will actually be on your right.  However, the manner of measuring and stating the window size and position should be consistent so that everyone is speaking the language at the quoting stage. That makes it easier and prevents possible problems when the envelope is produced.