Residential water hoses have varying flow rates, based on each hose's size and slope, as well as how intense the pressure of the faucet to which it is attached is.
Aubuchon Hardware gives a standard flow rate for residential water hoses, based on three factors: size, length, and water pressure. Small, inexpensive hoses around 1/2-inch (inside) diameter carry 9 gallons per minute (gpm); 5/8-inch diameter deliver 17 gpm, while the largest and usually higher quality 3/4-inch hoses delivers around 23 gpm --- nearly triple the water rate of the small hoses. In addition, when you purchase a hose, it typically indicates its water flow rate on the packaging.
If you wish to test the water rate of your hose, a simple way to do so is to turn the hose on full force, then time how long it takes to fill a 5- or 10-gallon bucket.
Complicated mathematical equations are also available to test the actual water rate of a hose. These equations utilize information such as the hose's diameter, its slope, and its length. Online calculators are available for you to simply input the information specific to your hose and arrangement to get the water rate.