If you plan on a window being 5/8" from the bottom, and 7/8" from the
left and the size 1-1/8" x 4-1/2", you should catch most addresses.
Remember that the address itself must have at least a 1/8" space on
all sides between it and the edge of the window.
California State University
"Normal window placement is ½" from the bottom and 7/8" from the left.
Window size is 1 1/8" x 4 1/2"."
Theoretically, nearly each envelope type and size may have a window,
this generally depends on the manufacturer. The most common (and
recommended by USPS) window size is 1 1/8 x 4 1/2, and the position
7/8 in from left and 1/2 (often 5/8) in from bottom, but there are
lots of variations.
Addressing and Printing Guidelines
The correct formatting and address position on an envelope is required
to facilitate mail processing by optical character recognition
equipment, used by many postal services for sorting mail.
Machine-readable mail can be sorted automatically, rather than by a
human, which results in faster and more accurate delivery.
Here is the picture that illustrates the correct address position:
600 Basic Standards for All Mailing Services
6.3 Window Envelope
For all letter-size and flat-size mail in window envelopes, every
character in the delivery address, including any postal barcode,
marking, or endorsement, must be completely visible through the window
throughout the full range of movement of the insert bearing the
delivery address. Any window envelope used for letter-size or
flat-size mail claimed at automation rates or for letter-size mail
claimed at Enhanced Carrier Route high density or saturation rates
must also meet the barcoding standards for letters and flats in
708.4.0. Any window envelope used for letter-size or flat-size mail
claimed at any other rate must meet the following additional
a. The address and any barcode visible through the window must be
printed on white paper or paper of a very light color.
b. A clear space of at least 1/8 inch is required between the address
block, which includes any optional endorsement line and any barcode,
and the top, bottom, and left and right edges of the address window,
and must remain when the insert is moved to its full limits in each
direction within the envelope to ensure efficient processing and
delivery. For nonautomation rate mail, the bottom edge of the address
window must not extend more than 1/8 inch into the barcode clear zone
as defined in 202.5.1. Any letter-size envelope containing a window
that intrudes into the barcode clear zone is not eligible for MLOCR or
RVE FASTforward processing options for the Move Update standard in
202 Elements on the Face of a Mailpiece
2.1 Address Placement Causing Mail to be Nonmailable and Nonmachinable
The location of the delivery address on a letter-size mailpiece
determines which dimensions are the length and height of the piece.
The length is the dimension parallel to the address as read; the
height is the dimension perpendicular to the length. Consequently, the
placement of the address may render a piece nonmailable or
nonmachinable. On a letter-size piece, the recommended address
placement is within the optical character reader (OCR) read area,
which is a space on the address side of the mailpiece defined by these
boundaries (see Exhibit 2.1, OCR Read Area):
a. Left: 1/2 inch from the left edge of the piece.
b. Right: 1/2 inch from the right edge of the piece.
c. Top: 2-3/4 inches from the bottom edge of the piece.
d. Bottom: 5/8 inch from the bottom edge of the piece.
Exhibit 2.1 OCR Read Area
d. If a window envelope is used, the clearance between the leftmost
and rightmost bars and any printing or window edge must be at least
1/8 inch, and the clearance between the barcode and the top and bottom
window edges must be at least 1/25 inch. These clearances must be
maintained during the insert's range of movement in the envelope.
Address block windows on heavy letter mail (as defined in 5.2, General
Barcode Placement for Letters) must be covered; such windows may be
covered on other mail. Covers for address block windows are subject to
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