A mini keg can come in various sizes, but a common size is five liters, or about 14 12-ounce beers. A standard full keg serves 165 beers. If you have 40 guests, each person can enjoy about four beers.

Farran Powell is the managing editor of investing at Forbes Advisor. She was previously the assistant managing editor of investing at U.S. News & World Report. Her work has appeared in numerous ...