A standard 5/8-inch garden hose has a flow rate of roughly 9–17 gallons per minute (GPM) at typical household water pressure of 40–60 PSI — which works out to about 600–1,000 gallons per hour (GPH). A larger 3/4-inch garden hose runs a higher flow rate, often 20-plus GPM, since the wider diameter lets more water through at the same pressure.
Actual garden hose GPM and GPH will vary hose to hose based on length, nozzle restriction, and your home’s water pressure, so if you need an exact number for a project, a quick bucket-and-timer test (fill a 5-gallon bucket and time it) gives you gallons per minute directly. If your water pressure or flow seems unusually low — well below the average garden hose flow rate for your hose size — that can point to a supply-line, pressure regulator, or fixture issue worth having a plumber look at. The 5 Star Plumbing team can test your home’s water pressure and flow rate if something seems off.