The diameter of a U.S. quarter is approximately 0.955 inches (24.26 mm). This measurement is standard for quarters minted in the United States. The quarter, which is worth 25 cents, features a design that includes George Washington on the obverse (front) and various designs on the reverse (back) depending on the series and mint year.
The size of the quarter is designed to be easily distinguishable from other coins, such as pennies, nickels, and dimes, which have different diameters. This helps in quick identification and handling of the coins in everyday transactions.