A jigger is a common bar essential that acts as a cocktail measuring cup. Jiggers are dual-sided and help bartenders cut down on overpouring and remain consistent when crafting cocktails. They have different capacities on each end and range from 0.5 to 2.5 ounces. One of their main advantages is that jiggers are dual-sided and allow bartenders to quickly mix drinks while using both sides of the jigger.