A quarter-pound beef patty, which is 4 ounces, is a standard size that many fast food burgers adhere to. Wendy's, Shake Shack, and Whataburger all use quarter-pound beef patties.
Certain fast food chains do not adhere to the quarter-pound measurement. For example, Five Guys uses 3.3-ounce patties, and McDonald's beef patties are either 1.6 or 4 ounces.