From front to back, a U.S. quarter, also called a quarter dollar, is 1.75 millimetres (0.0689 inches) thick. The diameter, which is the length of a line drawn through the middle of a round coin, is 24.26 millimetres (0.955 inches).
A quarter is made up of 91.67 percent copper and 8.33 percent nickel. The weight of a single quarter is 5,670 grammes. Since 1796, the United States Mint has been in charge of making quarters. Early quarters were made of silver, so the edges had to be trimmed or shaved to get the valuable metal. The edge of modern quarters is reeded or ridged so that the coin can’t be messed up. A quarter is worth 25 cents, but some old or rare coins can be very valuable—some can be worth thousands of dollars.