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
Window size is always specified as height x width regardless of orientation. Window positions are always measured by their distance from the left edge of the envelope and the distance from the bottom (the flap is the "top" of the envelope). If you would like to view and download window templates, please visit our templates page. These templates should be used for window reference only and should not be used for creating and sending envelope artwork. If you need help with your envelope artwork, please contact customer service.
Also see our tips on how to measure a block size.