Garden Hose Flow Rate Calculator
Calculate garden hose flow rate in GPM from diameter, length, and water pressure.
Compare 1/2, 5/8, and 3/4-inch hoses and estimate fill time for pools.
Garden hose flow rate is the volume of water delivered per minute. It depends on your home’s water pressure, the hose’s internal diameter, and the total length of the hose run. Friction loss — resistance from water moving against hose walls — increases with length and decreases with diameter.
Basic flow rate relationship:
Flow Rate (GPM) ≈ Pressure (PSI) / Friction Loss Factor
For practical gardening purposes, reference tables are more useful than the full Darcy-Weisbach equation.
Flow rate reference table at 40 PSI (typical residential supply):
| Hose Diameter | 25 ft / 7.6 m | 50 ft / 15 m | 100 ft / 30 m | 150 ft / 46 m |
|---|---|---|---|---|
| 1/2" (13 mm) | 9 GPM / 34 LPM | 6 GPM / 23 LPM | 4 GPM / 15 LPM | 3 GPM / 11 LPM |
| 5/8" (16 mm) | 17 GPM / 64 LPM | 12 GPM / 45 LPM | 8 GPM / 30 LPM | 6 GPM / 23 LPM |
| 3/4" (19 mm) | 27 GPM / 102 LPM | 19 GPM / 72 LPM | 13 GPM / 49 LPM | 10 GPM / 38 LPM |
Residential water pressure ranges:
- Low pressure: 20–40 PSI
- Normal: 40–60 PSI (most homes)
- High pressure: 60–80 PSI
- Above 80 PSI: may damage appliances — install a pressure regulator
Water usage applications and flow requirements:
| Use | Required Flow |
|---|---|
| Drip irrigation | 0.5–2 GPM |
| Soaker hose | 1–3 GPM |
| Hand watering | 2–5 GPM |
| Lawn sprinkler | 4–10 GPM |
| Pressure washer (residential) | 2–4 GPM at higher PSI |
| Filling a 5-gal bucket | Any rate — time it for actual GPM |
Choosing the right hose diameter:
- 1/2": Suitable for small container gardens and light hand watering
- 5/8": The most popular size — covers most residential gardening needs
- 3/4": Best for large gardens, long runs, or when feeding multiple sprinklers simultaneously
Water quantity formulas:
Gallons used = Flow Rate (GPM) × Minutes
Liters used = GPM × Minutes × 3.785
Worked example: A 5/8" hose, 75 ft long, watering for 20 minutes at 50 PSI: Approximate flow ≈ 9 GPM (interpolated from table) Water used = 9 × 20 = 180 gallons (681 liters)
At an average US water rate of $0.006 per gallon, this watering session costs approximately $1.08.