Assuming you are talking about a 5 gallon plastic bucket, the capacity is usually around 20 quarts or 18.92705 liters. However, the actual amount that can be held in a 5 gallon bucket will depend on the dimensions of the particular bucket and how tightly packed the contents are. For example, if you were to try to fit 5 gallons of water into a 5 gallon bucket, it would not all fit because water is a liquid and has space between each molecule. On the other hand, if you were to put 5 gallons of sand into a 5 gallon bucket, it would all fit because sand is a solid and the particles pack together tightly with no space in between them.