How many times can U.S. paper money be double folded before it tears?

According to the Bureau of Engraving and Printing, which is a section of the U.S. Department of the Treasury, paper money is durable enough that it can be double folded 4,000 times before the note tears. A double fold means folding first forward and then backward.

The paper for U.S. currency is made of 75 percent cotton and 25 percent linen. Each paper note weighs approximately 1 gram. The function of the Bureau of Engraving and Printing is to design and print money and other security products, such as identification cards and naturalization certificates. The highest-denomination note that the Bureau of Engraving and Printing ever printed was $100,000 Gold Certificate, which was printed from 1934 to 1935 and used just for transactions between the Federal Reserve Banks.