The average suitcase is about 50 liters in size. However, there are a variety of sizes and styles of bags, so the liter capacity can vary considerably. For example, carry-on luggage is usually much smaller, ranging from about 22 to 35 liters. If you're packing for a long trip or need to bring a lot of gear, you'll probably want a larger bag, such as an 80-liter duffel bag. Whatever size you choose, make sure it meets the requirements of your airline carrier.