Envelopes are not referenced by point thickness. They are referenced by lbs. ( # ) So a standard envelope is 24# and made with white wove paper. That is why you may sometimes see a printer referencing an envelope as "24# WW" or simply "24WW" Almost 90% of all commercial envelopes, such as #10, #9, #7, # 6 3/4, # 6 are made as 24# WW. When it comes to invitation envelopes for social announcements, like the A2, A7, A9, A10, etc, thicker papers are often used. It is common to see 28# WW and well as 32# WW. Not to complicate matters but there are two standards of numbers used to describe the thickness of text paper and beyond slight subtleties, there is no differences between the two! 20# is the same as 50#. 24# is the same as 60#. 28# is the same as 70#. 32# is the same as 80#. Take 24 lb (#) paper and 60 lb (#) paper. They're the same thickness, same texture, and same weight; they're used for the same thing and interchangeable when you order printing.