Editing Envelope (section)

=== North American sizes ===
There are dozens of sizes of envelopes available in the United States.

The designations such as "A2" do not correspond to ISO paper sizes. Sometimes, North American paper jobbers and printers will insert a hyphen to distinguish from ISO sizes, thus: A-2.

{| class="wikitable sortable"
|+ North American standard envelope sizes
|-
! Format !! Dimensions (in) !! Dimensions (mm) !! {{abbr|AR|Aspect ratio}} !! Suitable content format
|-
! A2 (Lady Grey)
| {{size|4+3/8|5+3/4|in|mm|ar=on}} || Letter paper folded twice ({{resx|{{frac|4|1|4}}|{{frac|5|1|2}}}})
|-
! A6 (Thompson Standard)<!--PWG?-->
| {{size|4+3/4|6+1/2|in|mm|ar=on}} || A2
|-
! A7 (Besselheim)<!--PWG?-->
| {{size|5+1/4|7+1/4|in|mm|ar=on}} || A6
|-
! A8 (Carrs)<!--PWG?-->
| {{size|5+1/2|8+1/8|in|mm|ar=on}} || A7
|-
! A9 (Diplomat)<!--PWG?-->
| {{size|5+3/4|8+3/4|in|mm|ar=on}} || Letter paper folded once ({{resx|{{frac|5|1|2}}|{{frac|8|1|2}}}}), A8
|-
! A10 (Willow)<!--PWG?-->
| {{size|6|9+1/2|in|mm|ar=on}} || 
|-
! C5
| {{size|6+1/2|9+1/2|in|mm|ar=on}} || 
|-
! No. {{frac|6|3|4}} (Personal)
| {{size|3+5/8|6+1/2|in|mm|ar=on}} || Personal check, US currency
|-
! No. {{frac|7|3|4}} (Monarch)
| {{size|3+7/8|7+1/2|in|mm|ar=on}} || 
|-
! No. 9 (A long)
| {{size|3+7/8|8+7/8|in|mm|ar=on}} || 
|-
! No. 10 (Business, Commercial)
| {{size|4+1/8|9+1/2|in|mm|ar=on}} || No. 9; letter paper folded into thirds ({{resx|{{frac|3|2|3}}|{{frac|8|1|2}}}})
|-
! No. 11
| {{size|4+1/2|10+3/8|in|mm|ar=on}} || No. 10
|-
! No. 12
| {{size|4+3/4|11|in|mm|ar=on}} || No. 11
|-
! No. 14
| {{size|5|11+1/2|in|mm|ar=on}} || No. 12
|}

The No. 10 envelope is the standard business envelope size in the United States.<ref>{{cite web |url=https://www.paperpapers.com/envelope-size-chart.html |title=Envelope Size Chart - Help understanding envelope sizes. |publisher=PaperPapers.com |year=2018 |access-date=13 February 2018 }}</ref>
PWG 5101.1<ref name="pwg"/> also lists the following even inch sizes for envelopes: {{resx|6|9}}, {{resx|7|9}}, {{resx|9|11}}, {{resx|9|12}}, {{resx|10|13}}, {{resx|10|14}} and {{resx|10|15}}.

Envelopes accepted by the U.S. Postal Service for mailing at the price of a letter must be:

* Rectangular
* At least {{frac|3|1|2}}&nbsp;inches high × 5&nbsp;inches long × 0.007&nbsp;inch thick.
* No more than {{frac|6|1|8}}&nbsp;inches high × {{frac|11|1|2}}&nbsp;inches long × {{frac|1|4}}&nbsp;inch thick.<ref>{{cite web |url=https://pe.usps.com/businessmail101?ViewName=Letters |title=Sizes for Letters |publisher=[[United States Postal Service|USPS]] |year=2016 |access-date=24 December 2016 }}</ref>
* Letters that have a length-to-height aspect ratio of less than 1.3 or more than 2.5 are classified as "non-machinable" by the USPS and may cost more to mail.<ref>{{cite web |url=https://pe.usps.com/cpim/ftp/manuals/qsg300/Q201.pdf |title=Physical Standards for Commercial Letters and Postcards |publisher=[[United States Postal Service|USPS]] |year=2018 |access-date=13 February 2018 }}</ref>