Garden Hose Water Flow Calculator

Diameter and Pressure:

Hose Length:

How to Calculate Garden Hose Water Flow

The garden hose water flow calculator estimates the water flow rate based on hose diameter, source pressure, and hose length, providing results in US gallons per minute (gpm), Imperial gallons per minute (gpm), and liters per minute (LPM). The calculation uses predefined flow rates adjusted for length and converts to all three units.

Base Flow Rate (US gpm):

\[ Q_{\text{US}} = F_{\text{base}} \times F_{\text{length}} \]

Imperial Flow Rate (gpm):

\[ Q_{\text{Imperial}} = Q_{\text{US}} \times 0.832674184603841 \]

Metric Flow Rate (LPM):

\[ Q_{\text{LPM}} = Q_{\text{US}} \times 3.78541178 \]

Where:

\( Q_{\text{US}} \): Flow rate in US gallons per minute (gpm)
\( Q_{\text{Imperial}} \): Flow rate in Imperial gallons per minute (gpm)
\( Q_{\text{LPM}} \): Flow rate in liters per minute (LPM)
\( F_{\text{base}} \): Base flow rate, determined by hose diameter and pressure (e.g., 4 for 1/2" at 20 psi or 12.5mm at 138 kPa)
\( F_{\text{length}} \): Length adjustment factor (e.g., 4 for 25' or 3 for 10m)
0.832674184603841: Conversion factor from US gpm to Imperial gpm
3.78541178: Conversion factor from US gpm to LPM

Select the diameter-pressure combination and hose length to compute the flow rates in all units.

Using the Garden Hose Water Flow Calculator

This calculator estimates water flow through a garden hose, providing results in US gpm, Imperial gpm, and LPM for irrigation or gardening tasks.

Select the hose diameter and pressure, then the hose length (in feet or meters). The calculator returns flow rates in all three units.

Example (Imperial): Calculate the flow rate for a 3/4" hose at 40 psi over 50 feet.

Diameter and Pressure: 3/4" - 40 psi (\( F_{\text{base}} = 18 \))
Hose Length: 50 feet (\( F_{\text{length}} = 2 \))
Flow Rate (US gpm): \( 18 \times 2 = 36 \) gpm
Flow Rate (Imperial gpm): \( 36 \times 0.832674184603841 \approx 29.976 \) gpm
Flow Rate (LPM): \( 36 \times 3.78541178 \approx 136.275 \) LPM

Example (Metric): Calculate the flow rate for a 19mm hose at 276 kPa over 15 meters.

Diameter and Pressure: 19mm - 276 kPa (\( F_{\text{base}} = 18 \))
Hose Length: 15 meters (\( F_{\text{length}} = 2 \))
Flow Rate (US gpm): \( 18 \times 2 = 36 \) gpm
Flow Rate (Imperial gpm): \( 36 \times 0.832674184603841 \approx 29.976 \) gpm
Flow Rate (LPM): \( 36 \times 3.78541178 \approx 136.275 \) LPM

Use this tool to plan water delivery efficiently across imperial and metric measurements.