What Is the CFS to GPM Converter?
This tool converts a flow rate measured in cubic feet per second (CFS) to gallons per minute (GPM) using US gallons. CFS is common in hydrology, river discharge, and large pumping or irrigation systems, while GPM is the standard unit for pumps, plumbing, and equipment specifications. Converting between them lets you compare measurements and size equipment correctly.
How to Use It
Enter your flow rate in cubic feet per second. The calculator multiplies it by the conversion factor and instantly displays the equivalent flow in gallons per minute. You can use whole numbers or decimals for fractional flows.
The Formula Explained
One cubic foot equals 7.48052 US gallons, and there are 60 seconds in a minute. Multiplying these gives \(7.48052 \times 60 \approx 448.831\). So $$\text{GPM} = \text{CFS} \times 448.831$$ This single factor captures both the volume conversion (cubic feet to gallons) and the time conversion (seconds to minutes).
Worked Example
Suppose a stream has a discharge of 2.5 CFS. Multiply: $$2.5 \times 448.831 = 1{,}122.08 \text{ GPM}$$ So 2.5 cubic feet per second equals about 1,122 gallons per minute.
FAQ
Does this use US or Imperial gallons? It uses US gallons. For Imperial (UK) gallons the factor would be about 373.73 instead.
How do I convert GPM back to CFS? Divide the GPM value by 448.831 to recover the flow in cubic feet per second.
Is the conversion exact? The factor 448.831 is rounded from 448.83117; results are accurate to a small fraction of a percent for practical use.
