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
Units of paper quantity the 500-sheet ream has become the de facto international standard. A paper bundle is a quantity of sheets of paper, currently standardized as 1,000 sheets. A bundle consists of 2 reams or 40 quires. As an old UK and US measure, it was previously equal to 960 sheets. When referring to chipboard, there are two standards in the US. In general, a package of approximately 50 pounds of chipboard is called a bundle. Thus, a bundle of 22 point chipboard (0.022" thick) 24" × 38", with each sheet weighing 0.556 pounds, contains 90 sheets. However, chipboard sold in size 11"