Convert GPM to CFS (Gallons Per Minute to Cubic Feet Per Second)

Gallons Per Minute to Cubic Feet Per Second Conversion Table

How to Convert GPM to CFS

To convert gallons per minute (GPM) into cubic feet per second (CFS), use these steps:

1. Convert gallons to cubic feet using:
   1 cubic foot = 7.481 gallons
   So, 1 gallon = 1 ÷ 7.481 ≈ 0.1337 cubic feet
2. Convert per-minute flow to per-second:
   0.1337 ft³ per minute ÷ 60 seconds = 0.002228 ft³/s

Thus, 1 GPM ≈ 0.002228 CFS.

Example: Convert 15 GPM to CFS

15 × 0.002228010407594 = 0.03342015611391 CFS

Real-Life Examples of GPM to CFS Conversion

Kitchen Faucet

Average flow rate: 2.2 GPM
2.2 ÷ 448.831 = 0.004903 CFS

Garden Hose

10 GPM = 0.02228 CFS

Fire Hose

200 GPM = 0.445875 CFS

Household Water Main

30 GPM = 0.066875 CFS

What Is GPM (Gallons per Minute)?

Gallons per minute (GPM) is a unit that describes how many gallons of liquid pass a given point in one minute. It’s used widely in plumbing, irrigation, and fluid mechanics.

• 1 US gallon = 3.785 liters
• 1 GPM = 3.785 L/min

GPM Formulas

From volume and time:
Q = V ÷ t

From pipe velocity and area:
Q = v × A
(Convert to gallons per minute afterward)

What Is CFS (Cubic Feet per Second)?

Cubic feet per second (CFS) measures the volume of fluid passing a point per second. One CFS equals one cubic foot flowing by in one second.

• 1 CFS = 1 ft³/s

CFS Flow Formula

Q = A × v
Where A = cross-sectional area (ft²), v = velocity (ft/s)

Or:
Q = V ÷ t
Where V = volume in cubic feet, t = time in seconds

Where Are These Units Used?

• Rivers: Stream flow rates in hydrology are expressed in CFS.
• Residential and commercial water use: Often measured in GPM.
• HVAC and fire suppression systems: Use both units depending on context.

Read more guideline here:

• USGS Streamflow Data
• EPA Water Conservation Tips

Related Tools

• GPM to LPM
• Gallon to Liter
• Gallons to Cubic Inches