Letter (paper size) "official" "Government Letter" size, , was used in government, while paper was standard in most other offices. In the U.S., paper density is usually measured in "pounds per ream" (of 500 sheets). Typical Letter paper has a basis weight of paper of – the weight of 500 sheets (a ream) of paper at and at 50% humidity. One ream of 20-pound Letter-sized paper weighs , and a single Letter-sized sheet of 20-pound paper weighs , which is equivalent to 75.19 g/m. Some metric information is typically included on American ream packaging. For example, 20-pound paper is also labeled as 75
Paper size (4:3 and 3:2) are ratios of small integers, unlike their ANSI (or ISO) counterparts. Furthermore, the aspect ratio 4:3 matches the traditional aspect ratio for computer displays. The size Arch E1 has a different aspect ratio because it derives from adding 6 inches to each side of Arch D or subtracting the same amount from Arch E. An intermediate size between Arch C and D with a long side of does not exist. The sizes listed above are for paper sold loose in reams. There are many sizes of tablets of paper, that is, sheets of paper bound at one