What Is the GPM to CFS Converter?
This tool converts a volumetric flow rate expressed in gallons per minute (GPM) into cubic feet per second (CFS). Both units describe how much fluid passes a point over time, but GPM is common in plumbing, pumps, and irrigation, while CFS is the standard for rivers, streams, channels, and hydraulic engineering. The conversion is universal — based on the fixed relationship between US gallons and cubic feet — so it applies anywhere.
How to Use It
Enter your flow rate in gallons per minute and the calculator instantly returns the equivalent flow in cubic feet per second. Use it to translate pump specifications into channel-flow units, compare irrigation rates, or feed values into hydraulic models.
The Formula Explained
The conversion comes from two facts: one US gallon equals 0.133681 cubic feet, and there are 60 seconds in a minute. Combining them gives \(1\ \text{CFS} = 448.831\ \text{GPM}\). Therefore:
$$\text{CFS} = \frac{\text{GPM}}{448.831}$$
Dividing your GPM value by 448.831 yields the flow in cubic feet per second.
Worked Example
Suppose a pump delivers 1,000 GPM. Then $$\text{CFS} = \frac{1000}{448.831} = 2.2280\ \text{CFS}.$$ So 1,000 gallons per minute is about 2.23 cubic feet per second.
FAQ
Is this for US or Imperial gallons? The factor 448.831 is based on US liquid gallons. Imperial gallons are larger, so a different factor would apply.
How do I convert CFS back to GPM? Multiply the CFS value by 448.831.
Why does river flow use CFS? CFS scales naturally to large open-channel volumes and pairs cleanly with cross-sectional area in feet for velocity calculations.
