1 Gallon = 4 Quarts [US, UK, fluid or dry]
For example, to find out how many quarts of water there are in a 5 gallons bucket, multiply the gallon value by the conversion factor, 5 * 4 = 20 quarts of water.
Note that 1 US gallon of pure or distilled water (sea water weighs more because of the salt in it) weighs about 8.345 pounds (lbs) or 133.5 ounces or 3.78 kilogram. 1 imperial gallon is about 10 pounds or 160 ounces or 4.54 kilograms.
Gallon and quart are volume measurement units in imperial and US customary systems. There are fluid and dry measurement for both units in US customary but in not imperial system. The abbreviation for gallon is "gal" and for quart "qt".