A quarter-barrel, often referred to as a pony keg, is a type of beer keg that holds approximately 7.75 gallons, or 29.3 liters, of liquid. This size is commonly used for smaller gatherings or parties, making it a popular choice for home brewers and bars alike. In terms of dimensions, a quarter-barrel typically measures about 16 inches in height and 12.8 inches in diameter. It is one-fourth the size of a standard full-size keg, which holds 15.5 gallons. This makes the quarter-barrel a convenient option for those who want to serve draft beer without the commitment of a larger keg.