How many tennis balls are used during the Wimbledon Championships each year?

Answer

55,000 tennis balls

New balls come in after the first 7 games and every 9 games after that, and they're kept chilled at 20°C until needed. Many used balls are sold to fans, and some have famously been donated as nesting homes for endangered harvest mice.

Source: All England Lawn Tennis Club (Wimbledon) official figures